1. Having an unknown or unacknowledged name: an anonymous author.2. Having an unknown or withheld authorship or agency: an anonymous letter; an anonymous phone call.3. Having no distinctive character or recognition factor: a very great, almost anonymous center of people who just want peace (Alan Paton).
ETYMOLOGY:
From Late Latin annymus, from Greek annumos, nameless : an-, without; see a1 + onuma, name (influenced by earlier nnumnos, nameless); see n-men- in Appendix I.