Omega

For ohm – SI unit of electrical resistance; formerly also used upside down (℧) to represent mho, the old name for the inverse of an ohm (now siemens with symbol S) used for electrical conductance. Unicode has a separate code point U+2126 Ω OHM SIGN (HTML entity Ω), but it is included only for backward compatibility, and the canonically equivalent code point U+03A9 Ω GREEK CAPITAL LETTER OMEGA (Ω) is preferred.[7]