(n.) The quality or state of being anonymous; anonymousness; also, that which anonymous.

anonym anonymity anonymous anonymousness camouflage camouflaged closed meeting closet concealed confidentiality confidentialness cryptonymic cryptonymous disguise disguised domino executive session false colors false face false front guisard guiser impersonator in disguise incog incognita inmost innermost innominate interior intimate inward isolated isolation mask masked masker masque masquerade masquerader masquerading mummer mummery nameless namelessness on the sly personal privacy private private conference privy protective coloration retired retirement secluded seclusion secretly sequestered sequestration smoke screen unacknowledged undefined under cover undesignated unidentified unknown unnamed unrecognizable unrecognized unspecified visor vizard vizard mask withdrawn without a name