out of circulation - if someone is out of circulation they are no longer taking part in social activities.

I hear she's back in circulation again after her accident.

• for the heck of it
• for the hell of it
• for the life of
• for the life of you
• for the long haul
• for the moment
• for the most part
• for the present
• for the record
• for the sake of argument
• for the taking
• for the time being
• for two cents
• forty winks
• for want of a better word
• for what it's worth
• foul-mouthed
• foul play
• foul up
• foul up something
• four corners of the earth
• four corners of the world
• four-letter word
• frame of mind
• Frankenstein's monster