om I. interjection alsoaum\ˈȯm\ Etymology: Sanskrit om — used in Hinduism, Sikhism, and Lamaism as a mantra in mystical contemplation of ultimate reality II. noun alsoaum\ˈōm, ˈȯm\ Etymology: Sanskrit om : a mantra consisting of the sound \ˈōm\ or \ˈȯm\ and used in Hinduism, Sikhism, and Lamaism in mystical contemplation of ultimate reality