The Latin verb "submoneo" is composed of two parts: the prefix "sub-" and the verb "moneo."

Sub- is a Latin prefix meaning "under," "beneath," "behind," or sometimes "secretly."

Moneo is a Latin verb meaning "to warn," "to advise," or "to remind."

Therefore, "submoneo" essentially means "to secretly advise" or "to secretly warn." The prefix "sub-" can add the nuance of doing something in a more subdued or subtle manner, while "moneo" provides the primary action of warning or advising.