The idiom of the day collection
down in the dumps
meaning:
depressed
I've decided to buy her some flowers because she looked down in the dumps.
an old flame
meaning:
somebody you were once in love with
Yesterday I come across an old flame of mine. I was head over heels in love with her.
to give somebody the boot
meaning:
to fire somebody from their job
'Because he isn't a good employee, I am going to give him the boot', said the CEO.
food for thought
meaning:
something to think about
What you've said has certainly given me food for thought.