I. stal ‧ wart 1 /ˈstɔːlwət $ ˈstɒːlwərt/ BrE AmE noun [countable]
someone who is very loyal to a particular organization or set of ideas, and works hard for them:
old party stalwarts
stalwart of
Rob’s a stalwart of the school’s chess club.
II. stalwart 2 BrE AmE adjective
[ Language: Old English ; Origin: stælwierthe 'useful, strong' , probably from stæl 'place' + wierthe 'worth' ]
1 . stalwart supporter/ally etc a very loyal and strong supporter etc
2 . formal strong in appearance
—stalwartly adverb