A pseudonym is a fictitious name used in place of one’s actual, or legal, name. Pseudonym is the most general term in this group and includes all of the others. It does not suggest any discreditable motive for concealing one’s identity; a pseudonym may be adopted merely because it is more striking or easier to recall than one’s actual name. Pen name and non de plume (a term supposedly coined in England from French elements) both refer specifically to a fictitious name that an author signs to a book, article or other literary work.

• Voltaire was the pseudonym (or pen name ) of Francois Marie Arouet; Lewis Carroll was the pseudonym (or nom de plume ) of Charles Dodgson.

An alias is a name taken to conceal one’s identity, often for suspect purposes. An alias is often assumed to avoid the consequences of a criminal record or to confuse officers of the law. On the other hand, a reformed criminal or a person who has been involved in a scandal may move to another area to make a fresh start and there take an alias to protect himself and his family from publicity. In the strict legal sense, alias is not only an assumed name but may be another name by which a person is known to some people. Unlike the other words, alias may be used adverbially: Jason Miller, ali as James Minton.

Nom de guerre (adopted from the French and meaning literally "war name") is a pseudonym adopted by a person who must conceal his true identity in order to retain freedom of action. Consequently, many persons engaged in various kinds of controversies or in political activities that are against a prevailing régime find it necessary to adopt nom de guerre .

• Lenin was the nom de guerre of Vladimir Ulyanov: Currer Bell was the nom de guerre (and the pen name ) of Charlotte Brontë because she found it easier to publish her works under a masculine name.