Thru-Hiker 

A hiker that completes a long distance trail in one calendar year.

This is commonly used when talking about the large 3 thru hikes: Pacific Crest trail (PCT), Continental Divide trail, and the Appalachian Trail.

Thru-Hike

The long distance trail.

An example would be, "I am going on a Thru-hike of the PCT."

Section Hike

When someone hikes a portion of the long trail. There is no set minimum or maximum mileage for a hike to be called a section hike.

It's just not a full completion of a trail in the same year.

Section Hiker

The person hiking the section.

There is also a phrase sometimes interchanged for this term: Slackpacker

Day Hiker

Someone who hikes for the day and goes home. They are generally seen around towns.

NOBO

A hiker going north bound on a trail. Or a plan to go north bound.

An example of this is that most hikers who hike the big 3, hike NOBO.

SOBO

A hiker that hikes south bound on a trail.

Both NOBO and SOBO are generally used when talking about full Thru-Hikes, but I have also used it while section hiking.

Terminus

The starting or ending point of the trail.

Flip Flop

When a hiker switches from going NOBO to SOBO, by driving to the other terminus and hiking down or up.

This is usually used when closures or fires happen on trail. There is no set point on trail to flip flop.

Tramily or Trail Family

This is the phrase for people you meet on trail that becomes family. Usually people around the same pace will stick together. They might not hike every mile as a group but they might do risky climbs or water crossing together. They tend to camp together too.

Tramilies are filled with amazing people, and can save you sometimes. Especially when you slide 30 feet on a snow ridge and almost go off a cliff- a story for another time.

Trail Angels

These are people off trail that help hikers out. This can be a water cache, a ride into town or a cooler with cokes. Big and small things are greatly appreciated. And anyone who helps are angels.

Trail Magic

The things trail angels do to help.

An example of this is "We had some good trail magic today, we got to refill on water and an apple"

Trail Legs

This is the point where you start getting your endurance for the miles you are doing. Once you get your trail legs, you start pulling bigger mile days. Plus you tend to get tired less often. This takes time to develop.

Trail Name

This is a nickname that is given to you while hiking, from hikers. Sometimes it is pulled from something that has happened on trail.

Vitamin I

Ibuprofen, this is used a lot on trail, because you are sore, blistered and tired. I try not to pop them daily, but sometimes you can't help but take some vitamin I.

Hiker Hunger

When you pull large miles, you will be hungry all.. the.. time.. You body will be compensating for the exercise you are doing. You will crave things you didn't pack out. Like Taco bell, or pizza. Sometimes these cravings will wake you up in the middle of the night or you will see a pine cone the shape of a chicken nugget, and won't be able to stop about McDonalds for the rest of the day.

Hiker Midnight

This is around 9 pm. When you are out camping and hiking, you body resets to the sun rise and sunset. And because you are waking up early and moving a lot during the day, generally around 9, you are pretty tired and ready to rest.

Many times after dark and if you are around other people, you should switch your headlamp to red light. Because its hiker midnight and someone could be sleeping.

Hiker Trash

This is generally the phrase for hikers who have just gotten back into town and haven't cleaned themselves up yet. When you are hiking days on end, you get gross and dirty. And when you roll back into town, you look somewhat homeless.

Cowboy Camping

This is when you throw you sleeping mattress and bag on the ground and pass out. Sometimes your mattress doesn't even make it out of your pack.

When it is warmer and nice weather, I like to cowboy camp to watch the stars at night.

The issues with cowboy camping are bugs and weather. You should always keep an eye on how cold it gets at night or if there is a lightning storm at 1 am before cowboy camping. Take it from me, waking up soaking wet is not fun.

Leave No Trace (LNT)

This is probably one of the biggest things to know before going into the woods. This is basically the idea that whatever you pack in you pack out: trash, certain waste products, anything you wouldn't want to walk by, shouldn't be left on trail, stopping places, or camp sites.

Many people don't use this and I've been to several camping spots that we cleaned up on trail, and several that we had to pass because how gross it is. Please learn proper LNT and use them during you time outdoors.