- flare (v.)
- mid-16c., originally "spread out" (hair), of unknown origin, perhaps from Dutch vlederen. Related: Flared; flaring. The notion of "spreading out in display" is behind the notion of "spreading gradually outward" (1640s). Flare-up "a sudden burst" is from 1837.
- flare (n.)
- "bright, unsteady light," 1814, from flare (v.), which led to the sense of "signal fire" (1883). Flares "flared trousers" is from 1964.