font (n.1)
"basin," Old English font, from Latin fons (genitive fontis) "fountain" (see fountain), especially in Medieval Latin fons baptismalis "baptismal font."
font (n.2)
"typeface, set of letters of a particular type," 1680s, earlier "a casting" (1570s), from Middle French fonte "a casting," noun use of fem. past participle of fondre "to melt" (see found (v.2)). So called because all the letters in a given set were cast at the same time.