[ I ] to burn brightly either for a short time or not regularly:

[ I ] also flare up When something bad such as violence, pain, or anger flares (up), it suddenly starts or gets much worse:

[ I or T ] to (cause to) become wider:

[ C ] a sudden increase in the brightness of a fire:

[ C ] a very bright light or coloured smoke that can be used as a signal, or a device that produces this:

[ C usually singular ] the fact of something, especially clothing, becoming wider at one end: