green-flag

Noun

green flag (plural green flags)

1. (literally) A flag that is green, used in motor racing to indicate the beginning or resumption of a race.
   • As we stood waiting for the departure time with the setting sun twinkling on the great brass dome of our 2-4-0, the sound of church bells was the only one apart from the measured tread of the guard slowly pacing towards his van, and, standing at an open window, I more than once heard the fireman's...1955 January, R. S. McNaught, “From the Severn to the Mersey by Great Western”, in Railway Magazine, page 19
2. (figuratively, informal) A sign or cue that signals a positive trait about someone or something.
   • When your partner is going through a tough time — whether on their own or with you involved — how do they manage those emotions? Do they bottle them up and repress their feelings, do they express them, or do they take them out on others? As [Dr. Marissa] Tunis explains, it's a major green flag if...2021 December 29, Lexi Inks, “15 Early Signs Your Relationship Has Long-Term Potential”, in Bustle, archived from the original on 03 Feb 2023