Sex
The word sex refers to the hormonal make up and reproductive structure with which a person is born. Or in others words, when an individual is born with ovaries, vagina and hormonal make up which is at par of these reproductive structures, the individual is said to possess a biological sex of a female, conversely, when an individual is born with penis and testis and hormonal make up which is at par with their reproductive organs, the individual is said to possess a biological sex of a male. Here, it should be made clear, biological sex and gender of a person may or may not be the same and the two words are not synonymous.
Also, when two individual conscientiously involves in copulation or intercourse with one another, the action is often term as sex in layman’s term. This is more of an abbreviation of the term sexual intercourse.