A very enjoyable part of love-making, in which the mouth, lips and tongue are used to stimulate a partner's genitals. Technically it relates to the act between any permutation of the sexes, but it is most commonly used to refer to a woman going down on a man.
Oral sex is particularly effective (for both sexes) if the woman kneels in front of the man, which puts her at the perfect height to take his swollen cock in her mouth. She can then lick, kiss, suck and generally adore his cock and balls with her mouth until her partner is stimulated to the point of ejaculation, whereupon she can (and ideally should) swallow his sperm. Women who dislike the taste of semen and who can deep throat
may prefer to let their partner shoot down their throat to avoid the taste buds altogether.
A talented cocksucker
can bring a man off from erection to orgasm with her mouth alone, but a light wanking action on the base of the cock can be productive. Some men will grip the woman's hair or head, either to encourage more action or to hold the head still while they thrust urgently into the woman's mouth in a vigorous fucking action. This can cause the woman to gag but should be tolerated if possible as it usually means an orgasm is close.
Oral sex can be performed simultaneously, when it is often referred to as 69
Oral sex doesn't have to progress to ejaculation, but can also be an extremely pleasant form of foreplay. Waking up a sleeping lover by sucking his cock gently to produce an erection is a particularly nice form of oral sex. Once a woman gets the taste for spunk, however, it can be difficult to resist the temptation to suck her lover all the way to climax in the desire to get a delicious mouthful. I speak from experience (and have the sore knees to prove it).