1. verb To cause someone to feel more passionate or excited about someone or something. In this usage, a noun or pronoun can be used between "fire" and "up." I know our players are nervous about the big game, but it's our job as coaches to fire them up.

2. verb To turn on a machine. In this usage, a noun or pronoun can be used between "fire" and "up." Well, fire up the coffee pot and tell me all about your date last night!

3. verb To light something, typically something to be smoked (such as a cigarette or pipe). In this usage, a noun or pronoun can be used between "fire" and "up." Come on, fire up those cigars, boys—we're celebrating!

4. verb, slang To smoke marijuana. He must fire up all day long because he's always stoned when I see him.

5. adjective Feeling very excited or passionate about something. The crowd is really fired up right now, so let's send out the starters for the game. Don't go and talk to the boss while you're all fired up like this—wait until you're calmer so you don't say something you'll regret.