late 14c., "sum of six pennies," from six + pence. As a specific British coin, from 1590s. Sixpenny (adj.) had a figurative sense "paltry, cheap, petty, worthless" by 1560s; sixpenny nails (early 15c.) cost so much per hundred.
sitz-bath
sitzkrieg
Siva
six
sixfold
sixpence
sixteen
sixteenmo
sixteenth
sixth
sixties