In human-computer interaction, a command verb is a word with special and specific meaning that appears in a user interface. For instance, the words "edit" and "view" and "help" which appear in the web browser menu are all clearly verbs. Other items such as "file" or "favorites" or "tools" are nouns, but the verb appears in the submenu, for instance, "save", "open", "send", "add to", or "organize".

A web page typically includes a few such verbs also, typically including "search", "log in" and perhaps "edit this page", as Wikipedia itself encourages you to do.

A reflexive user interface is one in which commands and perhaps other controls are defined in the interface itself. For instance, any Wikipedia policy can be edited by any user, and this has historically included a few verbs such as "revert" and "ban" that are not defined by mediawiki but by the social environment of Wikipedians.