Definition of singlet in English:



  • 1British A sleeveless garment worn under or instead of a shirt; a vest.

    • ‘Tommy is wearing a baseball cap, a singlet and combat shorts, revealing several tattoos.’
    • ‘Winter has settled in, you're not wearing a singlet under your business shirt and you have your first sneeze… she thinks you caught pneumonia and you're going to die.’
    • ‘Alas, after a while, the sight of board shorts, singlets, jandals and sunglasses will make you wince.’
    • ‘Equally as beautiful as his womenswear, this featured plain white singlets studded with gold sequins, low-slung cream trousers and kimono print shirts.’
    • ‘Others had on only singlets and cotton trousers as they jumped into the water.’
  • 2Physics
    A single unresolvable line in a spectrum, not part of a multiplet.

    • ‘The singlet is detectable as a quintet at room temperature in methemoglobin with identical spectral features to those of the well characterized tyrosyl radical in photosystem II.’
    • ‘To break supersymmetry using the F-term, one can add chiral multiplets that transform as singlets under the gauge symmetries in the theory.’
    • ‘Superimposing such a diffractive structure on an aspheric surface yields an achromatic singlet whose spherical and chromatic aberrations are corrected.’
    1. 2.1 A state or energy level with zero spin, giving a single value for a particular quantum number.
      • ‘A small singlet-triplet energy gap is known to favor intersystem crossing.’
      • ‘Energy can be transferred from the singlet state to the triplet state via intersystem crossing.’
      • ‘The reorganizational energy of the singlet ET was also calculated from the temperature-dependent data and found to be 0.89 eV.’
      • ‘Its superconductivity is often assumed to be unconventional in that the Cooper pairs are not in a spin singlet state with s-wave symmetry, as with conventional superconductors.’
      • ‘Do aggregates of A2E have a higher singlet-oxygen quantum yield rather than monomers?’
  • 3Chemistry
    An atomic or molecular state in which all electron spins are paired.

    as modifier ‘singlet oxygen’
    • ‘And where does the singlet oxygen, the energy source, come from?’
    • ‘The origin of the initial spike observed upon detection of singlet oxygen luminescence remains unresolved.’
    • ‘It can thus be regarded as a simultaneous excitation of two triplets, whose coupling generates an overall singlet state.’
    • ‘The study of the excited states properties has shown that its photoreactivity in neutral aqueous medium is singlet initiated.’
    • ‘However, reactive oxygen species generated by UVA radiation, particularly singlet oxygen, can also damage nucleic acids.’


Mid 18th century (originally denoting a man's short jacket): from single (because the garment was unlined) + -et, on the pattern of doublet.