A term symbol is a unique 'nickname' for an electronic state. Term symbol is an abbreviated description of the total angular momentum quantum numbers in a multi-electron atom. However, even a single electron can also be described by a term symbol. Each energy level of an atom with a given electron configuration is described by not only the electron configuration but also its own term symbol, as the energy level also depends on the total angular momentum including spin. The usual atomic term symbols assume L-S coupling (also known as Russell–Saunders coupling or spin-orbit coupling). The ground state term symbol is predicted by Hund's rules.
Term symbol for a particular atomic state or free ion term is written as-
2S + 1LJ
Where-
2S + 1=Spin multiplicity and J=total angular momentum