I. card ‧ board 1 /ˈkɑːdbɔːd $ ˈkɑːrdbɔːrd/ BrE AmE noun [uncountable]
stiff thick brown paper, used especially for making boxes:
a sheet of cardboard
II. cardboard 2 BrE AmE adjective
1 . made from cardboard:
a cardboard box
2 . [only before noun] seeming silly and not real:
a romantic novel full of cardboard characters