In a sudden, offhand, abrupt, random, or headlong manner; abruptly; suddenly; all at once.Dashing; offhand; abrupt; free, careless, or happy-go-lucky; rash or random; impetuous: as, a slap-dash manner; slap-dash work; a slap-dash writer.n. A composition of lime and coarse sand, mixed to a liquid consistency and applied to exterior walls as a preservative; rough-casting; harling.n. The outside plaster filling of a half-timbered house, between the beams.n. Offhand, careless, happy-go-lucky, or ill-considered action or work.n. Violent abuse.To do in a rough or careless manner.To rough-cast (a wall) with mortar.