I seem to remember having come across the word "avuncular" used as a noun, as, for example, in the sentence "You are a perfect avuncular," whereas the word is most usually used as an adjective. Is its use as a noun recorded anywhere (perhaps as achaic usage), or might the speaker have meant to say "avunculus" instead of "avuncular"?
The term avuncular as a noun came up in a TV Episode of Agatha Christie's Hercule Poirot when he was squiring a young recent heiress. (Episode S10 Ep1 The Mystery of the Blue Train 11 Dec. 2005). Whereas the characters English is not always conventional, others in the episode to that noun in stride. Hercule said something to the effect, "Then I will accompany you. I will be your avuncular." However, I have all three Webster's unabridged dictionaries (1909, 1934, 1961) and none of those mention it as a noun. The first two just refer to the word literally as an adjective for uncle. The first two also mention what the third doesn't. That is that the adjective was used to refer humorously to a pawnbroker.