What is the definition of” the one?”

A specified person 

The one" is a phrase with no real definition. it's different for every person. when you're with "the one," you'll know. the feelings you get when you are with that person are indescribable. it's a very different feeling from all other feelings...

The one who has some of the same interests as you
The one who likes you for who you really are
The one who doesn't like you for your looks only
The one who cares about you

Some one that is different from anyone else you have been with… they are the only one that gives you this certain feeling inside… the one that can make you happier than you've ever been.

If you find the person who completes you in all ways, good and bad, mentally and physically...then you found them.

Wishing you the best. This is one of those things that you can "just know" but spend a life time getting to know.