aboriginal (adj.)

"person, animal, or plant that has been in a country or region from earliest times," 1858, mistaken singular of aborigines (1540s; aboriginal is considered the correct singular in English), from Latin aborigines "the first inhabitants," especially of Latium, hence "the first ancestors of the Romans." This is possibly a tribal name, or from or made to conform to the Latin phrase ab origine, which means literally "from the beginning."

This is from ab "off, away from" (see ab-) + ablative of origo "a rise, commencement, beginning, source; descent, lineage, birth," from stem of oriri "arise, rise; be born, be descended, receive life" (see origin).

It was extended by 1789 to natives of other countries which Europeans had colonized, especially "aboriginal inhabitant of Australia," with capital A-. The Australian English slang shortening Abo is attested from 1922 as a noun, by 1906 as an adjective.

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).