Etymology
Etymology is the study o the history o wirds, thair origins, an hou thair form an meanin an pronunciation hae chynged ower time.
Sum leids are descended from a common parent leid, like French an Spaingie are sib leids an baith cum frae Laitin, so aften they baith hae a lot o wirds in common thae soond similar an mean awmaist the same thing.