on fire

Meaning

1. Being burned by fire.
2. Overwhelmed with emotion; beside oneself.
3. Excited, enthusiastic or passionate.
4. Doing very well; achieving good results at a rapid rate.
5. (informal) Sexually aroused.
6. Experiencing a burning-like sensation, especially "the burn" (from buildup of lactic acid)

Synonyms

catch fire

burn

ablaze

alight

burning

afire

aflame

in flames

burnt

aflare

become burnt

fiery

lighted

red hot

switched on

consumed by fire

very hot

burns

Etymology

Inherited from Middle English: on fier

In summary

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