Noun
A cock connected with four pipes or ports, and having two or more passages in the plug, by which the adjacent pipes or ports may be made to communicate; formerly used as a valve in the steam engine, and now for various other purposes.
(slang) A contraption devised of two double dildoes joined crossways, so that four people can be penetrated at the same time, or two in two holes each
Source: en.wiktionary.org