: something or someone designated with the name omega or the Greek letter ω especially denoting the last in position, order, or class
"Omega-3" refers to the position of the final double bond in the chemical structure, which is three carbon atoms from the "omega," or tail end of the molecular chain. Ruairi Robertson
4
a
: a negatively charged elementary particle that has a mass 3270 times the mass of an electron
called alsoomega minus
b
: a very short-lived unstable meson with mass 1532 times the mass of an electron
called alsoomega meson
Word History
Etymology
Middle English, from Greek ō mega, literally, large o