1. a sleeveless undershirt or athletic shirt
Usage: chiefly British
2. a wrestling uniform consisting of a one-piece tight-fitting garment
Usage: sports
3. an unpaired electron in an atom or molecule
Usage: chemistry; physics

Examples

• He wore a cotton singlet under his dress shirt.
• The wrestler adjusted his singlet before the match.
• She put on a singlet and shorts for her morning run.
• The team’s singlets were bright red with white numbers.
• The molecule contains a singlet oxygen atom.
• He preferred singlets to regular t-shirts in hot weather.