The dough that makes up the exterior of tamales is known as masa. This shouldn't be confused with masa harina, which is a kind of corn flour often used in tamales (as well as corn tortillas and more).

I know the word “masa” means dough, particularly corn dough, but it might as well be short for “miracle,” because the process of producing this staple of Mexican (and other Central and South American) ...

Simply translated, masa — the foundation for every perfect tortilla, tostada, tamale, pozole, arepa and gordita — means dough. It unites North and South America, defying any one cultural identity.