to happen suddenly.

Severe thunderstorms flare up there at almost any time during the summer.

You may not feel like chopping vegetables when the pain in your hands flares up.

Etymology: based on the literal meaning of flare up (= to suddenly burn brightly)

• avail yourself of something
• avant-garde
• average out to
• average out to something
• a vicious circle
• a voice in the wilderness
• avoid like the plague
• avoid someone like the plague
• avoid something like the plague
• a volte-face
• a wake-up call
• a walk of life
• a war of nerves
• a war of words
• a waste of breath
• a watched pot never boils.
• a way of life
• a weak link
• a weak link in the chain
• a wet blanket
• a wet dream
• a whale of a
• a whale of a bill
• a whale of a difference
• a whale of a job