Failing comes from fail + -ing. Fail derives from Old French faillir ('to be lacking, fail'), from Vulgar Latin *fallire, from Latin fallere ('to deceive, disappoint'). Morphologically, the account is both compositional and suffixal: -ing marks the visible structure by which the older base becomes the modern form. In present use, it is used as a noun and preposition meaning "a weakness or shortcoming in character or ability", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes related forms such as fail, failure, and fallible, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Old French faillir and Latin fallere, keeping the history tied to concrete forms rather than a loose resemblance. Its semantic neighborhood is marked by weakness, shortcoming, flaw, and fault on one side and contrasts such as strength, virtue, and merit on the other, locating the modern specialization without adding a new origin story.