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Definition [Mens] waterproof jacket

Mens technical mountaineering jacket designed to perform in the harshest conditions. Durable, breathable, full unadulterated storm protection.

Definition [Mens] waterproof jacket Reef blue
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12 years in the making, our fully waterproof and breathable Definition Jacket is engineered to cope with whatever you, the mountains, and the weather can throw at it.

'The Definition is arguably as good or better than some jackets costing twice as much. The cut is sleek and efficient, components are top-notch... the unbranded fabric works well and feels reassuringly tough. The effective helmet-compatible hood means you can use it for anything from full-on mountaineering to general hill-walking' Outdoors Magic

The Definition jacket is a fortress, it is designed to face the foulest, wettest, windiest, snowiest, wildest weather. Fully featured and tough as old boots, this is the jacket that will take whatever abuse you want to throw at it, from Scottish winter, alpine climbing to Munro bagging. 

Definition is breathable and waterproof. Its face fabric and backer are manufactured from tough nylon for superb durability. Sandwiched between these is a waterproof / breathable PU/PTFE membrane; the result is the best combination of durability and breathability available in heavier weight 3 layer fabric. It is our most durable jacket yet.

Fit for purpose doesn’t just mean waterproof - it has to fit you! Definition is designed to sit over your other layers, its cut is tuned so that it does not ride up to expose your back or tum when you swing your axes above your head. The hood is large enough to fit over a climbing helmet and deflect spindrift from engulfing your core.

The mountains are a changeable environment and you are not always going to want to be locked down. Definition can be adapted as conditions change or your work rate varies. Inverted vent zips for quick climate control - the vent position also means you can access the pockets on your inner layers without undoing the jacket.

We know you are going to be wearing a rucksack a lot of the time so we have designed the placement of the pocket and vent zips to stay clear of your shoulder straps and hip belt, or climbing harness. 

Fast hood adjustment, wired peak, chest pockets, draft excluders, pit zips for ventilation, internal storm flaps, YKK AquaGuard zips all contribute to the full package.

Definition is destined to become a faithful companion on your epic adventures for years to come.

Key features
  • 3 Year Alpine Bond
  • Helmet compatible hood with wired peak, front adjusters and easy-grab rear adjuster
  • 2-way opening YKK Vislon AquaGuard front zip
  • Internal storm flap with bottom snap and chin guard
  • 2 map sized hand pockets (positioned above harness/ waist belt) with YKK AquaGuard zips
  • 1 external chest pocket with YKK AquaGuard zip
  • 2 core body venting YKK AquaGuard zips, inverted for ease of use
  • Gusseted cuffs with anti-snag Velcro adjustment
  • Embedded Cohesive hem adjusters, accessible from inside hand pockets or at the hem
  • 1 internal YKK zipped chest pocket
More images
Vital stats

145 gsm 3 layer fabric, Hydrostatic head: 30,000 mm, MVTR: 20,000 g/sqm/24hrs
Face: 40 D x 90 D Nylon
Backer: 20 D Nylon tricot
Bi-component PU/PTFE membrane
YKK Aquaguard zips


M: 515 g

Origin: China

Environmental Considerations

The chemical finish that keeps water beading off your waterproof jacket has changed.

As with all waterproofs from responsible outdoor brands, our waterproof jackets meet international environmental standards and require occasional washing with a technical wash to maintain their high breathability.

This wasn’t always the case. Years ago, waterproof jackets were treated with chemicals that had toxic by-products that lingered in the environment for generations. Those old chemicals needed little maintenance, whereas modern waterproofs need regular washing.

We fully support this change. In fact, we quite like the idea of taking time to look after our kit so that it lasts a long time.

We are committed to reducing the environmental impact of all our products –in fact it’s in our DNA: we can’t imagine ever doing anything else. We always review the materials we use, manufacturing methods and our own consumption of resources. We do the research, make informed decisions, and choose the best option available to us.

Product Care Information

To maintain the high performance of your waterproof, we recommend you wash and re-proof once or twice a year using specialist products like Nikwax or Grangers. For more information, read our detailed care instructions.

Size chart
Men's sizing
Chest (inches) 37" 40" 43" 46" 49"
Waist (inches) 30" 32" 34" 36" 38"
This size chart indicates the body measurements our garments are designed to fit. Measure yourself as described below, and use the size chart to find your size.
Chest: measure around your chest at the widest part. The tape measure should pass under your arms, and be level from front to back.
Waist: measure around your waist at the narrowest part.
Hips: standing with your feet together, measure around your hips at the widest part.
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What You Say: Customer Reviews and Comments

12 Reviews


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This jacket is amazing. I am yet to use it in the mountains, but after several canoeing and camping trips in bad weather it hasn't let me down. The cuffs are amazing, miles ahead of any other jacket I have used. Water just doesn't get in and yet I can easily get a pair of gloves tucked in underneath. The whole cut, in general, is brilliant, not at all restricting and yet with enough room for layering. In fact, the whole jacket is just brilliant and from a really nice company, bought this from the Ambleside store and the staff were really nice. Top notch Jacket!

Craig O
Excellent Hard Shell

Just come back from a week of walking in Snowdonia, it rained all day every day! This jacket kept me dry throughout and never wetter out. It also survived being caught on barbed wire with no damage to show for it!

A superbly designed jacket

The tailored fit allows easy movement and just the right amount of room for layering without feeling baggy or flapping in the wind, the sleeve length is perfect. It doesn't ride up at full stretch and the hood fits fine with or without a helmet. The fabric feels bomb proof, and has kept me totally dry in torrential downpours and hours of drizzle. It has decent breathability to boot. There are lots of ergonomic design features. I trust this jacket to perform well and to keep on performing in UK hills and mountains when other significantly more costly jackets have disappointed me.


I've used this jacket in anger about 20 times in the last couple of months. First for a very wet Scottish winter climbing trip, and then for a scalding ski trip in the French alps. I stayed completely dry through torrential rain, and pleasantly cool in the sun.

The fit is fantastic, more athletically cut than the ME Lahotse jacket (that the Definition can easily compare to). Comfortable for all day mountain slogs, and warm enough for standing around in car parks in the peak district.

My only criticism would be the pit zips. The placement makes them easier to use than the traditional underarm zips. However, because they are not over your hot armpits they didn't feel as effective as those on other jackets.


Used this jacket in Chamonix skiing this week and it was fantastic. Completely waterproof and windproof and a great fit. Way better than jackets for twice the price from the famous skiing brands.

Just awesome

Just used this jacket for a week of winter mountaineering in Scotland, including the wrath of storm Doris. The jacket was outstanding! Excellent breathablity and totally wind proof in what was gusting up to 70mph at times. Love it!

Matt S
Great Jacket!

I have used this jacket a few times for skiing since I bought it and I love it! It totally blocks out the wind and is still very breathable. Looking forward to taking it out the Scottish highlands for a bit of mountaineering and climbing in a couple of weeks time. Great job guys! grin

Proper Job

A good waterproof is an expensive essential for any mountain walker with prices now eye watering for the best kit. But yet again Alpkit have bucked that trend with a well thought through jacket at a sensible price. At 500g it saves 250g off the jacket it replaces and yet is sturdy and windproof (and well tested in the lakes this December!). At this level good waterproofing and breath-ability is a given as are the layout of pockets. I'm 6'2" and wear an XL. If I wanted a shaped fit I'd probably go for a L but the size up works well over fleeces or jackets. I have a Kabatic to give insulation and the colour co-ordinated combination work brilliantly. The location of pit zips is interesting. Alpkit have moved them lower on the jacket so you dont have to faff under your pack shoulder straps. This means that they no longer ventilate your hot underarm, more the back. We'll see if works in the longer term but is a good example of how this company dont just follow fashion, but are willing to think through technical problems with a fresh eye. At £210, it's a bargain and well worthy of five stars.

Great jacket but....

Performs well. The one gripe is the way the hood cords are tightened. The push buttons just do not work properly and the cords slip. One has never worked properly at all but I didn’t wear the jacket for a while after I got it so it was a bit late to say. Normal cord holders would be better. Hence 4 stars.

Definition Waterproof

I bought the jacket over a year ago after my berghaus paclite jacket finally gave up after 10 years. So far its done 2 winter seasons in the caingorms going mixed climbing and numerous scout weekends and dog walks. It is still 100% waterproof and the fit is really good with space underneath for big fleeces to keep warm. I'm 6'2" so bought a size large and the sleeves are nice and long as is the back length so it doesn't ride up. The material seems to be very tough and has survived ice axe points going in the wrong direction.

It would get 5 stars but I find the pockets go too far down the jacket and so when I put my hipbelt on I need to shuffle everything in them up so they don't get squished. The side vents are a little hard to operate but they don't get covered by your rucksack straps so that evens it out.


Great jacket. But doesn't quite compete against the Mountain Equipment Changabang. Zip in/out snow skirt and a shoulder zip pocket would make it perfect.

Great jacket for price but not quite up there yet

I just bought this jacket as been meaning to replace my old ME Changabang Pro Shell jacket (about 14 years old!). And i saw in a review is was a good contender. The price attracted me albeit i have always worn Goretex in the past so this will be my first daring breakaway. not used in Anger (clearly as it's a Heatwave ) but i would say it's a heavier fabric than my old jacket and a lot heavier than the new Goretex Pro versions. and no ski pass pocket is a mistake, a zip out snow curtain would be nice too. That being said, some good features, looks great so at £189 (sale price) i'll give it a go.

What They Say: Kudos - Product Reviews from independent magazines and websites

Outdoors Magic Definition Review

Alpkit’s full-on mountaineering shell, the Definition is reassuringly burly but properly refined – think James Bond reincarnated as a waterproof jacket. And the price is fantastic.


Outdoors Magic February 2017 - Jon Doran

OM Reviews 2016/17 New Product

immediately impressive

Outdoors Magic

Outdoors Magic December 2016 -

UKC reviews Definition

Definition screams good design


ukclimbing.com January 2017 - Dave Saunders

Trail Magazine Approved

Trail Magazine: Definition & Balance Waterproofs

Trail Magazine October 2017 - Trail Magazine