Appreciate means to value something. It also means to be thankful of what you have.

a term of polite rejection used by prospective employers, girlfriends and perhaps other people whose approval you seek. It generally means "I really don't give a crap, but objectively speaking, I suppose it's possible that someone else might."

A pejoritive for the phrase "go down on him/her" ... In replace of "to give oral pleasure to"

moaning at each other

an overwhelming feeling of gratitude - for example when someone uber generously gives you some music off their ipod.. and a fair bit resultant love goes into that word too.

ap·pre·ci·a·tion   uh-pree-shee-ey-shuhn

noun
1.
gratitude; thankful recognition: They showed their appreciation by giving him a gold watch.
2.
the act of estimating the qualities of things and giving them their proper value.
3.
clear perception or recognition, especially of aesthetic quality: a course in art appreciation.
4.
an increase or rise in the value of property, goods, etc.
5.
critical notice; evaluation; opinion, as of a situation, person, etc.

It's like thank you, but on steroids