den ‧ i ‧ er /ˈdeniə $ -ər/ BrE AmE noun [uncountable]
[ Date: 1400-1500 ; Language: Old French ; Origin: name of a coin, from Latin denarius , from deni 'ten each' ]
a unit for measuring how thin ↑ nylon , silk etc thread is
10-/15-/20– etc denier
a pair of 15-denier tights