Insult fallacy. No, liberty is not the origin of the word 'liberal'. The origin of the word 'liberal' is 'liberal'. It means to apply freely, without restraint (as in government, hair shampoo, ketchup, etc). The word is French in origin. It first began to be used in the 16th century as someone who is free of restraint in speech or action (like a criminal or a crazy person). Etymology is somewhat of a hobby of mine, you see.
Dictionaries do not define words. They standardize pronunciation and spelling, and give examples of the use of a word, but no dictionary defines any word. No dictionary owns any word.