An archaic or obsolete term possibly referring to festive dress, adornment, or celebratory attire, though historical usage is extremely limited.
Possibly from gay plus the -ment suffix (indicating a state, action, or result), though documentation of this word is sparse and it may be a very rare or regional formation.
This appears to be an extremely rare word—it might be a one-off coinage from some historical text that didn't catch on. English allows speakers to create new words by adding -ment, but most of these inventions fade away.
Complete word intelligence in one call. Free tier — 50 lookups/day.