In one Tamil dialect of Sri Lanka, aum simply means yes
Om is chanted across Hinduism, Buddhism, Jainism and Sikhism as the sound of ultimate reality. Yet nobody agrees where the word came from. One leading theory traces it to a Dravidian word for yes, and speakers of Jaffna Tamil in Sri Lanka still answer aum when they agree.
Om, also spelled Aum, first appears in the Vedic texts, where it is treated as a compressed form of the chants of the Samaveda. It often opens and closes chapters of the Vedas and Upanishads and is sung before prayers, during puja, at weddings and other rites of passage, and in meditation. Its written form is counted as the single most important symbol in Hinduism, standing for Brahman, the ultimate reality, and for Atman, the self within.
Its origin has been argued over since antiquity. The Upanishads themselves offer several Sanskrit derivations, including words for yes and roots meaning to urge or to attain. In 1889 Maurice Bloomfield linked it to a Proto-Indo-European introductory particle. The Indologist Asko Parpola instead proposes a borrowing from a Dravidian word meaning it is so or let it be, related to modern Tamil for yes. The syllable carries many other names, such as Pranava, the primeval sound, and Omkara, the Om-maker; in Sikhism the phrase Ik Onkar, one Om-maker, is an epithet of God.
Pronunciation hides a history. In Classical Sanskrit the vowel is a long o, so the word sounds like a nasal ōm. That o descends from an older Vedic diphthong, which is why some groups spell and chant it as three sounds, a-u-m. The Aitareya Brahmana matched those three parts to three stages of cosmic creation. In the Vedic Brahmanas the vowel was often held three times as long as normal, a style the Arya Samaj movement keeps as more authentic.
The familiar curling symbol is a cursive joining of letters in Devanagari, and Unicode encodes it twice, once as a Devanagari letter and once as a generic symbol. Bengali, Tamil, Kannada and other scripts write it in their own ways. It spread widely in Southeast Asia: the Khmer used it from the 1st century in the kingdom of Funan, and it appears on Cambodia's royal arms and in Thai sak yant tattoos. A 1921 claim that the swastika began as an Om monogram was judged unproven in Nature the next year.
Source: Om
