The male reproductive organ used for sexual intercourse that in the human male and some other mammals is also used for urination; the tubular portion of the male genitalia (excluding the scrotum).
A testis: the male sex and endocrine gland, found in some types of animals, that produces sperm and male sex hormones, including the steroid testosterone.
Either half of the structure that contains the testes: one side of the scrotum and its contents, considered as one object (one half of the ballsack, including its ball).