something thing, a

Something occasional or transient, as in For most free-lance musicians, work is a sometime thing. This idiom gained currency in the title of a song by George Gershwin, “A Woman Is A Sometime Thing” (1935), introduced in the folk opera Porgy and Bess.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.