1560s, "a molded projection which crowns the part to which it is affixed," from French corniche (16c.) or directly from Italian cornice "ornamental molding along a wall," perhaps from Latin coronis "curved line, flourish in writing," from Greek koronis "curved object" (see crown). Perhaps influenced by (or even from) Latin cornicem, accusative of cornix "crow" (compare corbel). Sense of "ornamental molding running round the walls of a room just below the ceiling" is from 1660s.

1660s, "part of a pedestal between the base and the cornice," from Italian dado "die, cube," from Latin datum (see die (n.)). Meaning "wood paneling on the lower part of a wall in a room" is by 1787.