mid-15c., "turned away in mind or feeling, disliking, unwilling," from Old French avers "hostile, antagonistic" and directly from Latin aversus "turned away, turned back," past participle of avertere "to turn away," from ab "off, away from" (see ab-) + vertere "to turn" (see versus). Originally and usually in English in the mental sense, while averted is used in a physical sense.

Averse applies to feeling, adverse to action: as, I was very averse to his going: an adverse vote: adverse fortune. [Century Dictionary, 1906]

1590s, "a turning away from;" 1650s in the figurative sense of "mental attitude of repugnance or opposition," from Middle French aversion (16c.) and directly from Latin aversionem (nominative aversio), noun of action from past participle stem of aversus "turned away, backwards, behind, hostile," itself past participle of avertere "to turn away" (see avert). Aversion therapy in psychology is from 1946.

"resembling or pertaining to birds," 1861, from Latin avis "bird" (from PIE root *awi- "bird") + -an.

1570s, from Latin aviarium "place in which birds are kept," neuter of aviarius "of birds," from avis "bird," from PIE root *awi- "bird." 

"art or act of flying," 1866, from French aviation, noun of action from stem of Latin avis "bird" (from PIE root *awi- "bird"). Coined 1863 by French aviation pioneer Guillaume Joseph Gabriel de La Landelle (1812-1886) in "Aviation ou Navigation aérienne."

"aircraft pilot," 1887, from French aviateur, from Latin avis "bird" (from PIE root *awi- "bird") + -ateur. Also used c. 1891 in a sense of "aircraft, flying-machine." Feminine form aviatrix is from 1927; earlier aviatrice (1910), aviatress (1911).