Copulation refers to the physical act of sexual reproduction, typically involving penetration. Intercourse specifically refers to sexual activity involving penetration of the vagina by the penis. So, while all intercourse involves copulation, not all copulation necessarily involves intercourse.
During sexual intercourse between a man and a woman, the man places his penis inside the woman's vagina. This is known as vaginal intercourse. Sexual intercourse could refer to any type of sexual activity in which one partner penetrates another. Other "types" of sexual intercourse include anal intercourse and oral intercourse.
Kind of a fuzzy line between the two, Relations could include any sexual contact as well are the mental, physical, emotional and romantic aspects of the sexual relationships between people. Sexual intercourse would probably be more narrowly considered as the singular act of sexual intercourse.
Sexual intercourse.
Sex can be "any activity from casual intimacies such as kissing and caressing to more intense types of physical contact designed to produce orgasm". This being said, I seem to recall a "presidential" statement that may have muddied the definition for many generations. Sexual activity (sex) can complement sexual intercourse or stand alone as a means for gratification. The penis/vagina are not the only methods of producing sexual enjoyment; humans beings can give and receive intense pleasure without any direct genital contact which is what sexual intercourse means.
"Intercourse" commonly refers to sexual activity between people, typically involving penetration. It can also refer to communication or interaction between individuals or groups.
Copulation is another name for sexual intercourse, which refers to the physical act of two individuals engaging in sexual activity.
If you are referring to human sex, it is the act of engaging in sexual activity, typically involving sexual intercourse between a man and a woman. This activity is a natural part of human biology and reproduction.
Sex is any form of sexual activity, especially intercourse. And yes, it's fun.
"Foreplay" typically refers to sexual activity that precedes intercourse. It can include kissing, touching, and other forms of intimacy that help build arousal and anticipation before engaging in sexual intercourse.
Its not technically sex in terms of sexual intercourse (sex). Though it may be considered a sexual activity.
Fornication refers to consensual sexual intercourse between two individuals who are not married to each other.