underpants / knickers
mutande
moo-TAN-deh
Colloquial: 'mutande'. More formal alternatives: 'slip' (m) for men's briefs, 'slip' (f) for women's knickers.
Compra le mutande di cotone al supermercato.
She buys cotton underpants at the supermarket.
Le mutande vanno cambiate ogni giorno.
Underpants should be changed every day.