His popularizing treatise on algebra, compiled between 813–33 as Al-Jabr (The Compendious Book on Calculation by Completion and Balancing), […] The English term algebra comes from the short-hand title of his aforementioned treatise (الجبر Al-Jabr, transl. “completion” or “rejoining”).
From this dude’s wiki page:
Oh okay, there we go. Thanks.