"melodic phrase in jazz," 1935 (but said to have been used by musicians since c.1917), of uncertain origin, perhaps a shortened form of riffle, or altered from refrain. The verb is attested from 1942, from the noun. Also in extended use. Related: Riffed; riffing.
[1953+; fr reduction in force]
[origin unknown; perhaps echoic; perhaps fr refrain; perhaps fr riffle or ripple in the sense of ''try, shot, crack'']
A refrigerator car; reefer1 (1950s+ Railroad)