The Gaulish language, and presumably its many dialects and closely allied sister languages, left a few hundred words in French and many more in nearby Romance languages, i.e. Franco-Provençal (Eastern France and Western Switzerland), Occitan (Southern France), Catalan, Romansch, Gallo-Italian (Northern Italy), and many of the extinct or nearly extinct languages of France and Belgium collectively known as langues d'oïl (e.g. Walloon, Norman, Gallo, Picard, Bourguignon, and Poitevin).
What follows is a list of inherited French words, past and present, along with words in neighboring or related languages, all borrowed from the Gaulish language (or more precisely from a substrate of Gaulish).
References
List of French words of Gaulish origin Wikipedia(Text) CC BY-SA