The word 'trilby' originates from the title of George du Maurier's 1894 novel Trilby, which was later adapted into a popular stage play. The eponymous heroine, Trilby O'Ferrall, was an artist's model in Paris. In the stage version of 1895, the actor playing the character Svengali wore a soft felt hat of this style, which subsequently became fashionable and was named after the play. Thus, the term demonstrates a clear path from a fictional character's name to a specific item of apparel, solidifying its place in the lexicon of fashion.

This word is a simplex proper noun turned common noun. It does not contain separable, productive morphemes in modern English.