alt (1)

in Internet use (for example alt.right), it is from alt.* in the newsgroups naming system in Usenet. The term was introduced in 1987 and is said to be short for alternative, as it was meant to be outside the usual newsgroup administrative controls and thus include groups on controversial topics and pornography.

alt (2)

"high tone," 1530s, originally in music, ultimately from Latin altus "high" (literally "grown tall;" from PIE root *al- (2) "to grow, nourish").

updated on September 18, 2022

Definitions of alt from WordNet

alt (n.)
angular distance above the horizon (especially of a celestial object);
Synonyms: elevation / el / altitude
Etymologies are not definitions. From, not affiliated with etymonline.