Definition of singlets:
(n) :
A single piece of clothing, particularly:
(n) :
(UK, Australia, Ireland, Nigeria, New Zealand, Singapore) A sleeveless buttonless shirt with a low-cut neck.
(n) :
(sports) A one-piece, tight-fitting uniform, usually made of spandex or nylon, required in wrestling and powerlifting.
(n) :
A set of one, an item not part of a larger set, particularly:
(n) :
(physics) A multiplet having a single member, especially a single spectroscopic peak.
(n) :
(physics, quantum mechanics) A quantum state having zero spin.