col ‧ la ‧ gen /ˈkɒlədʒ ə n $ ˈkɑː-/ BrE AmE noun [uncountable]
[ Date: 1800-1900 ; Language: French ; Origin: collagène , from Greek kolla ( ⇨ ↑ collage ) + French -gène 'producing' ]
a ↑ protein found in people and animals. It is often used in beauty products and treatments to make people look younger and more attractive.