noun

• A set of one, an item not part of a larger set, particularly:
• A set of one, an item not part of a larger set, particularly:
  "2003, Timothy M. Cox, 90: Protoporphyria, Karl M. Kadish, Kevin M. Smith, Roger Guilard, (editors), The Porphyrin Handbook, Volume 14: Medical Aspects of Porphyrins, page 132, When a ground state molecule absorbs a photon, the values of the electron spins are not altered and thus the primary excited state is the singlet state."
• A set of one, an item not part of a larger set, particularly:
  "Singlet and monocultural identity is so normalized that many voice hearers and plurals don’t share their experiences with anyone, living in isolation (and sometimes in poverty) and spending considerable inner resources to manage postures and performances of ‘mental health’."
• A single piece of clothing, particularly:
  "Winston wrenched his body out of bed — naked, for a member of the Outer Party received only 3,000 clothing coupons annually, and a suit of pyjamas was 600 — and seized a dingy singlet and a pair of shorts that were lying across a chair."