What is the meaning of Sissy?

An effeminate boy or man.

A timid, unassertive or cowardly person.

A male crossdresser who adopts feminine behaviours.

Sister; often used as a term of address

Effeminate.

Cowardly.

Urination; urine.

To urinate.

To sissygasm (reach orgasm solely by penetration of the anus).

Source: wiktionary.org