term symbols

Symbols characterizing the states of atoms and molecules in terms of multiplicity, symmetry of the total electronic wavefunction, and sometimes total (orbital + spin) angular momentum. Examples: $2 P 1 / 2$ denotes an atomic state of multiplicity 2 (doublet), electron orbital angular momentum quantum number $L = 1$ , and orbital plus spin angular momentum quantum number $J = 1 2$ .

Source:

Green Book, 2nd ed., p. 28