1. The collective name for three semistable baryons with charges of +1, 0, and -1 times the proton charge, designated Σ⁺, Σ⁰, and Σ^-, all having masses of approximately 1193 megaelectronvolts, spin of ¹/₂, and positive parity; they form an isotopic spin multiplet with a total isotopic spin of 1 and a hypercharge of 0.

2. Any baryon belonging to an isotopic spin multiplet having a total isotopic spin of 1 and a hypercharge of 0; designated Σ_J^P(m ), where m is the mass of the baryon in megaelectronvolts, and J and P are its spin and parity; the Σ_3/2+(1385) is sometimes designated Σ*.