What does "cuckoldry" mean?

Cuckoldry: The state of being a cuckold; the practice of making cuckolds. CUCKOLD'S KNOT Cuck"old's knot` (kk"ldz nt`). (Naut.) A hitch or knot, by which a rope is secured to a spar, the two parts of the rope being crossed and seized together; -- called also cuckold's neck. Ham. Nav. Encyc.

Sources