1. (internet) The email folder where incoming mail arrives.
2. (at the table) The mouth.
3. (in bed) The vagina.
Check your inbox. You have mail.
Inbox can be used as a verb, mostly on Facebook. To inbox someone is to send them a message to their message inbox - simple as it sounds.
On Facebook wall posts
Person 1 "Why is my life so awful?!"
Person 2 "What's the matter hun?"
Person 1 "I can't say on here, I'll inbox you"
transitioning from the popular sexual terminology coined by the construction industry (ie. nailed, screwed, hammered, banged etc), hi-tech nerds have one of their own:
a reference to a woman's vagina
Doomf8One: "Did you pass Doom level 41 last night?"
hellaUCLA: "I didn't play- I was at my girlfriend's place last night and her Mac sucks!"
Doomf8One: "ROFL! That's lame"
hellaUCLA: "It was cool- I was in her inbox all night instead!"