noun1. a stopper for the vent hole of a cask
2. a tap, usually of wood, fitted to a cask
3. a US name for tap2 (sense 1)
4. a short cylindrical projection on one component designed to fit into a hole on another, esp the male part of a joint (spigot and socket joint) between two pipes
Word origin
C14: probably from Old Provençal
espiga a head of grain, from Latin
spīca a point