There are many synonyms for the term "undercover man," depending on the context in which it is being used. Some of the most commonly used synonyms include "secret agent," "covert operative," "spy," and "intelligence officer." Other possibilities include "mole," "informant," "double agent," "sleeper agent," and "infiltrator." Each of these terms carries its own connotations and may be appropriate in specific situations. For example, a "double agent" is someone who is posing as a member of one organization while secretly working for another, while an "infiltrator" is someone who is trying to gain access to a group or organization in order to spy on them or disrupt their activities.