omega

Concise Oxford English Dictionary © 2008 Oxford University Press:
omega /ˈəʊmɪgə/

▶noun

• 1 the last letter of the Greek alphabet (Ω, ω), transliterated as ‘o’ or ‘ō’.

• 2 the last of a series; the final development.

▶symbol (Ω) ohm(s).

– origin from Gk ō mega ‘the great O’.