OM is a commonly used acronym for the french football club Olympique Marseille.
OM is the only french team to win the Champions League.
Other Men's Sperm - children a woman has from a previous relationship that aren't yours.
I don't mind having sex with her once in a while, but that's as far as it'll ever go. She's got three kids and I can't be bothered with OMS.
Acronym for "Oh My Swift!" generally used by the millions of awesome Swifties worldwide in praise of The Fearless One, Taylor Swift. Similar to the over-rated and over-used OMG, but more.. FEARLESS. Usually used to express great joy, happiness and all the awesomeness of being a Swifty.