—adj. 1. overspread or covered with clouds; cloudy: an overcast day. 2. Meteorol.(of the sky) more than 95 percent covered by clouds.
3. dark; gloomy.
4. Sewing.sewn by overcasting.
—v.t. 1. to overcloud, darken, or make gloomy: Ominous clouds began to overcast the sky. 2. to sew with stitches passing successively over an edge, esp. long stitches set at intervals to prevent raveling.
—v.i. to become cloudy or dark: By noon it had begun to overcast.
—n. 1. Meteorol.the condition of the sky when more than 95 percent covered by clouds.
2. Mining.a crossing of two passages, as airways, dug at the same level, in which one rises to pass over the other without opening into it. Cf. undercast (def. 1).