Mantra is a Sanskrit word that is used in Hinduism and Buddhism to refer to a sacred utterance, prayer, or CHANT. It is believed to have spiritual and psychological power. The two-letter solution for the crossword clue 'Mantra' is 'OM', which is a sacred syllable used in meditation and prayer. The five-letter solution for the crossword clue 'Mantra' is 'CHANT', which is a repetitive vocalization of words or sounds used in meditation and prayer.