old flame

Concise Oxford English Dictionary © 2008 Oxford University Press:
flame/fleɪm/

▶noun

• 1 a hot glowing body of ignited gas that is generated by something on fire.

• 2 a thing compared to a flame's ability to burn fiercely or be extinguished: the flame of hope.

• 3 a brilliant orange-red colour.

• 4 informal a vitriolic or abusive email or newsgroup posting, typically one sent in quick response to another.

▶verb

• 1 give off flames.

  ■ set alight.

• 2 (of an intense emotion) appear suddenly and fiercely.

• 3 (of a person's face) become red with embarrassment or anger.

• 4 informal send an abusive email to.

• 5 (flame out) (of a jet engine) lose power through the extinction of the flame in the combustion chamber.

• 6 (flame out) informal, chiefly N. Amer. fail conspicuously.

– phrases
old flame informal a former lover.

– derivatives
flameless adjective,
flamer noun (Computing, informal),
flamy (also flamey) adjective .

– origin ME: from OFr. flame (n.), flamer (v.), from L. flamma ‘a flame’.