Anonymously

[ə'nɑnəməsli]

(adv.) without giving a name; 'she wrote these letters anonymously'.

Editor: Roxanne--From WordNet

(adv.) In an anonymous manner; without a name.

Edited by Barrett

It was introduced delicately; anonymously as it were. Charlotte Bronte. Villette.
Never mind the commoners, whom we will leave to grumble anonymously. William Makepeace Thackeray. Vanity Fair.

Edited by Barrett