to flare up

I flared up.

a flash of wit

to flash a smile

to flash one’s ivories

to flash through one’s mind

flash in the pan

in a flash

It flashed through my mind.

to be flat

to be flat on one’s face

as flat as a pancake

He is flat-footed

to go flat

to be flat broken

flat broke

flat footed

flat out

flatfoot

flatliner

to flatter a person

to be flattered and cajoled

Flattery will get you nowhere!

to flavour of

flawless