Teachers! Could you tell me the exact meaning of 'finger'!

I have consulted the webster college dictionary for the meanings of the word 'finger'. But I don't get it!
What I know now is that the meanings of 'finger' is only the apparatus of hand!
Could you tell me other meanings?

Thanks very much!

There are a couple of possibilities. To "finger" somebody is "tell on" that person. For example, if you knew that Mr. X committed a certain crime and the police were asking you about the crime and you "fingered" Mr. X you would be telling them he was the culprit.

Then there is "give somebody the finger", which is to make an obscene gesture with the middle finger.

:)

It also has a sexual connotation in BE. ;-)