What is the meaning of Pinhead?

The head of a pin.

A foolish or stupid person.

A telemark skier.

A human head that is unusually tapered or small, often due to microcephaly, or a person with that trait. Often promoted in freak shows as "human pinheads".

A newborn cricket used as food for pets.

The immature juvenile fruiting body of a mushroom prior to its gills opening.

Source: wiktionary.org