Contronym

[5][6] Some pairs of contronyms are true homographs, i.e., distinct words with different etymologies which happen to have the same form.

For example, sanction—"permit" or "penalize"; bolt (originally from crossbows)—"leave quickly" or "fix/immobilize"; fast—"moving rapidly" or "fixed in place".

Greek δημιουργός gave Latin its demiurgus, from which English got its demiurge, which can refer either to God as the creator or to the devil, depending on philosophical context.

In Hawaiian, for example, aloha is translated both as "hello" and as "goodbye", but the essential meaning of the word is "love", whether used as a greeting or farewell.

The Italian greeting ciao is translated as "hello" or "goodbye" depending on the context; the original meaning was "at your service" (literally "(I'm your) slave").