A quick one from the OED:

The word algebra comes from Arabic “al-jabr” (“the mending of broken parts”), entering Middle English via Italian, Spanish, and Medieval Latin in the sense “the setting of broken bones”. The modern mathematical sense comes from the title of a book, “ilm al-jabr wa’l mukabala” (“the science of restoring what is missing and equating like with like”), by the 9th-century Muslim mathematician Abu Ja'far Muhammad ibn Musa. His nickname “al-Kwarizmi” (literally “the man from Kwarizm”, now Khiva in Uzbekistan) is the root of the word “algorithm”.

So now you know who to blame for all those long afternoons in GCSE Maths.