on fire

prep_phrase

Etymology: From Middle English on fier, on fijre, on fire, on fyire, on fyre.

1. Being burned by fire.

   “If the wind picks up and the flames spread, the whole town could go on fire.”

2. Overwhelmed with emotion; beside oneself.

   “Anytime I am on fire with anxiety about the future, or totally freaking out that I am not being seen, heard, or treated fairly based on my old wounds, it is easy for me to RECOGNIZE that my Character 2 has flared right up in an attempt to not only protect me but help me get my needs met.”

3. Excited, enthusiastic or passionate.

   ““I'm on fire with an idea,” the 48-year-old businessman proclaimed with excitement similar to that which he projected in 1971 when his company became the first predominantly Black-owned corporation to be listed on the American Stock Exchange.”

4. Doing very well; achieving good results at a rapid rate.

   “That striker has scored four goals so far – he's on fire!”

5. Sexually aroused.
6. Experiencing a burning-like sensation, especially "the burn" (from buildup of lactic acid)

   “He locks us into a crouched position that results in muscle failure of the quads, hamstrings, and calves. It hurts. We raise ten-pound rubber rifles and hold them parallel to the ground. Our legs are on fire, then our arms too.”