nom de guerre /ˌnɒm də ˈɡeə $ ˌnɑːm də ˈɡer/ BrE AmE noun ( plural noms de guerre (same pronunciation) ) [countable] formal
[ Date: 1600-1700 ; Language: French ; Origin: 'war name' ]
a name that someone uses instead of their real name, especially someone who is fighting in a war