What is the meaning of Privy?

Private, exclusive; not public; one's own.

Secret, hidden, concealed.

With knowledge of; party to; let in on.

An outdoor facility for urination and defecation, whether open (latrine) or enclosed (outhouse).

A lavatory: a room with a toilet.

A toilet: a fixture used for urination and defecation.

A partaker; one having an interest in an action, contract, etc. to which he is not himself a party.

Source: wiktionary.org