Ok. This is not the word that CAPCH was looking for, then. But this is not what I found at the dictionary.
This is another definition:
of a man) make (another man) a cuckold by having a sexual relationship with his wife.
• (of a man's wife) make (her husband) a cuckold.
Yes, I´ve had a look at a few definitions since this thread started, and many don´t mention the nuances that I associate with the word.
However, I would still say that it is little-used. Despite some references to its current usage, I personally have yet to hear it used in modern spoken English. I have only ever encountered it in old literary works, where it always depicted a man who was unaware of his wife´s infidelity and was therefore unaware that he could be raising another man´s children.
This link gives an interesting insight into the word´s history:
http://dictionary.sensagent.com/cuckold/en-en/