The word 'whence' originates from the Old English hwanon, meaning "from what place." This Old English term is an adverbial formation from the interrogative base hwa- (who, what), which traces back to the Proto-Indo-European root kʷo-, the stem of interrogative and relative pronouns. Over time, the Middle English form whannes or whennes was simplified to 'whence.' Its core logic has remained consistent: it functions as a formal or archaic adverb and conjunction to denote origin or source, directly linking the ancient concept of questioning ("from where?") to its modern usage indicating derivation.

The word is a simplex form derived from Old English hwanon, which itself is an adverbial genitive form of hwan (from where). It is of Germanic origin.