(idiomatic, chiefly Scotland, Ireland, Liverpudlian, slang) a stupid person; a nutcase

A bolt with a hexagonal head.

A screw with a hexagonal head.

A screwdriver whose handle and hexagonal head are at right angles.

(two-up) A crooked organiser of a two-up game, who would cheat players out of their money.

A knot, or any of various similar kinds of knot, resulting in a ball of rope. / (Caribbean) The melon cactus. / (California) Any of several species of Echinocactus.

Of a sheet of paper: having the sender's name, address, etc. preprinted at the top. / (in combination) Having a head with specified characteristics. / (in combination) Having hair of a specified color.

simple past tense and past participle of head

(in combination) Heading in a certain direction.

(intransitive) To begin moving away. / (transitive) To intercept. / (transitive) To avoid the undesirable consequences of; prevent. / (intransitive) To start out. / (nautical) To turn away from the wind.