Lexically recognized synonym for "humblebrag"?

As one might guess, a humblebrag is one who uses a pretense of humility as a vehicle for boasting. This word can be found at Urban Dictionary but, it appears, nowhere more authoritative. Yet, of course, the concept is neither new nor esoteric; and one would expect there to be a word to cover it. Of course, we have the idea of false humility and could speak of one who is falsely humble or who is guilty of false modesty.

But isn't there a noun to denote the person who behaves in this way, and an adjective to describe him?

Solution 1:

A term you might consider if you want to appear modestly learned is Aristotle's eirôn, a noun variously translated as ‘the mock-modest’ or ‘the self-deprecating’ or ‘the reserved’. Aristotle describes the eirôn as more acceptable than the alazôn, ‘braggart’ or ‘exaggerator’ but not so admirable as the truthful man:

Mock-modest people, who understate things, seem more attractive in character; for they are thought to speak not for gain but to avoid parade; and here too it is qualities which bring reputation that they disclaim, as Socrates used to do. Those who disclaim trifling and obvious qualities are called humbugs and are more contemptible; and sometimes this seems to be boastfulness, like the Spartan dress; for both excess and great deficiency are boastful. But those who use understatement with moderation and understate about matters that do not very much force themselves on our notice seem attractive. And it is the boaster that seems to be opposed to the truthful man; for he is the worse character. —Nicomachaean Ethics, IV, 7

Eirôn gives its name to irony; the word itself doesn't appear to be in the dictionaries, but it had considerable currency in the LitCrit industry for the generation after Northrop Frye made the term central in The Anatomy of Criticism (1957). You'll find it in Abrams and Harpham, A Glossary of Literary Terms. Here's a modern history of the term from a 1991 work, The Critical Mythology of Irony.