What is the meaning of Dicky?

A louse.

Dicky dirt = a shirt, meaning a shirt with a collar.

A detachable shirt front, collar or bib.

A hat, especially (in the US) a stiff hat or derby, and (in the UK) a straw hat.

A seat behind a carriage or early motor car, for a servant.

A seat in a carriage, for the driver.

The luggage storage compartment of a sedan/saloon style car.

the buttocks.

A leather apron for a gig, etc.

A small bird; a dicky-bird.

An insignificant sound or thing; dicky-bird.

A pilot.

A hedge sparrow.

A donkey.

A haddock.

In bad condition; weak, faulty, unreliable, doubtful, troublesome.

A penis (dick).

Like a dick, foolish or obnoxious.

Source: wiktionary.org