Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Nom \Nom\, n. [F. See Noun.] Name.
Nom de guerre, literally, war name; hence, a fictitious name, or one assumed for a time.
Nom de plume, literally, pen name; hence, a name assumed by an author as his or her signature.
Wiktionary
n. A pseudonym.
WordNet
Usage examples of "nom de guerre".
Xu was greatly taken aback to hear himself being called by his nom de guerre.
Paula and two or three other German girls who had known her in Norway and travelled to the Low Countries at the same time as herself all believed that she had assumed her Norwegian nom de guerre to avoid the unwelcome attentions of a wealthy young Dutchman.
It was Tiger Face, Lei Yixiao, whose voice matched his nom de guerre.
His attempts to track Sethos down and murder him strongly suggested that either, (a) Sethos did know where the tomb was located, and el-Hakim (I preferred my nom de guerre to the anonymous X the others used) was aware of this.
Everybody made a fuss over him, and he actually gave himself a nom de guerre: X9, like the Alex Raymond character whom I had read about in the Awenturoso comics.