What does "hat" mean?

Additional senses

1. 2.sing. pres. of Hote to be called. Cf. Hatte. [Obs.] "That one hat abstinence." Piers Plowman.
2. 3.A covering for the head; esp., one with a crown and brim, made of various materials, and worn by men or women for protecting the head from the sun or weather, or for ornament. Hat block, a block on which hats are formed or dressed. -- To pass around the hat, to take up a collection of voluntary contributions, which are often received in a hat. [Collog.] Lowell.