se ‧ quin /ˈsiːkwən, ˈsiːkwɪn/ BrE AmE noun [countable]
[ Date: 1500-1600 ; Language: French ; Origin: Italian zecchino , from zecca 'place where coins are made' , from Arabic sikka 'coin' ]
a small shiny flat piece of metal, sewn onto clothes for decoration
—sequined, sequinned adjective