The word "unavowed" originates from the Middle French word "innavoer" meaning "to disavow" or "to reject". The prefix "un-" in English denotes negation or absence, while "avow" means to admit or confess openly. Therefore, "unavowed" suggests something that is not openly acknowledged or confessed.
As for the phrase "most unavowed", it is a combination of a superlative modifier "most" and the adjective "unavowed". This phrase intensifies the meaning of "unavowed" and emphasizes the covert or undisclosed aspect even further. However, it's important to note that "most unavowed" is not a common collocation or widely used phrase in everyday English.