vis ‧ cous /ˈvɪskəs/ BrE AmE adjective
[ Date: 1300-1400 ; Language: Late Latin ; Origin: viscosus , from Latin viscum 'mistletoe, sticky substance used for catching birds' ]
technical a viscous liquid is thick and sticky and does not flow easily:
As the liquid cools, it becomes viscous.
—viscosity /vɪˈskɒsəti, vɪˈskɒsɪti $ -ˈskɑː-/ noun [uncountable]