The sex organs, narrowly defined, are those parts of the body which are involved in sexual reproduction. The genitals are those sex organs visible from the outside.
The human sex organs include:
- penis, scrotum (holding the testicles), prostate, seminal vesicles
- vulva (which includes the clitoris and labia), vagina (which has the G-spot and the cervix), fallopian tubes, ovaries
More generally and popularly, the term sex organ refers to those parts of the body commonly associated with sexual excitement and arousal. The larger list would certainly include the buttocks and anus, the prepuce, the female breasts, and the nipples of both genders.