moser /moʊˈseəɹ/noun 1verb 1forms 5 noun1 •(Judaism) An informer; one who tells on another. verb1 •(Judaism) To inform or snitch on someone.Allegedly the Congregation had mosered [informed against him] that Papa's patriotism was doubtful, the journal was threatened with being closed down; well, now you know everything. — 1938 formsmosered · mosering · mosers · moserim · mosrim