I. cos 1 BrE AmE , 'cos, coz /kəz/ conjunction British English spoken informal
because:
I don’t get out much now cos of the children.
II. cos 2 BrE AmE noun ( plural coses, cos ) [uncountable and countable] British English
a type of ↑ lettuce SYN romaine
III. cos 3 /kɒz, kɒs $ kɑːs/ BrE AmE technical
the written abbreviation of cosine