Cuckold definition : cuckolds can be married men to any male in domestic relationship with a woman in which he remains exclusive and she does not. The husband usually finds pleasure through that of his wife and they (the wife and extra-marital participant) may both enjoy attempting to actively include him in the act of cuckolding as much as possible through serving her. Some common themes include praising her appearance, attempting to stimulate her sexually at the same time as the additional participant, and generally being engrossed in her enjoyment, usually while masturbating or involving himself in some sexual act with his wife during their activity.
“Cuckold” is derived from the Old French for the Cuckoo bird, “Cocu” with the pejorative suffix -ald. The earliest written use of the Middle English derivation, “cokewold” occurs in 1250. The females of certain varieties of Cuckoo lay their eggs in other bird’s nests, freeing themselves from the need to nurture the eggs to hatching. In medieval Europe, the law, custom, and the church all defined married women as a category of property held by her husband. Although Christian marriage vows strictly enjoined sexual exclusivity in a marriage for both partners, custom and doctrine rarely enforced it on the husband. A married woman who was unfaithful to her vows made a “cuckoo” of the husband who unknowingly provided her, and potentially her illegitimate offspring, with shelter and protection as a tricked bird does to the cuckoo’s eggs.
A nuance of the word often overlooked in contemporary usage is that it refers to a man who, like the bird warming the cuckoo’s eggs, is unaware of his victimization. A man who knows and acquiesced, in his wife’s taking of another lover was called a “wittol,” itself a derivation from the Middle English for “willing (as in knowing) cuckold.” From Wikipedia