adjective. Not accepted or recognized.

Not acknowledged; not recognized: as, an unacknowledged agent or consul.

Not owned; not confessed; not avowed: as, an unacknowledged crime or fault.

Not noticed; not reported as received: as, his check has remained unacknowledged.

adjective. Not acknowledged

adjective. not openly acknowledged

adjective. not recognized or admitted

"Not coincidentally, this is the group most likely to become the target of the contempt and thus the very public venom of extremists on the far-right and the far-left, working in unacknowledged but full concert, keen to neutralize people they see as spineless, bloodless sell-outs."

unacknowledged note  

secret  unappreciated  unavowed  unconfessed  undeclared  

conjectural  deep-rooted  recognize  unappreciated  unattained  

anonymous  cryptonymic  cryptonymous  forgotten  hidden