I. riff 1 /rɪf/ BrE AmE noun [countable]
[ Date: 1900-2000 ; Origin: Probably from ⇨ ↑ refrain 2 ]
1 . a repeated series of notes in popular or ↑ jazz music:
a guitar riff
2 . a piece of speech in which someone talks about a subject in an entertaining way that does not seem planned:
He goes off on a riff about the problems of being middle-aged.
II. riff 2 BrE AmE verb [intransitive]
1 . to play different notes related to the main tune in popular or ↑ jazz music:
He was riffing on his guitar.
2 . to talk about a subject in an entertaining way that does not seem planned:
During her show, she riffs about everything from her family to global warming.