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;" 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). Extended 1789 to natives of other countries which Europeans have colonized, especially "aboriginal inhabitant of Australia." Australian slang shortening Abo attested from 1922 (n.), 1906 (adj.).

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)).