Eliot had set out his own ideas about 'the new (the really new) work of art' in his essay 'Trad-ition and the Individual Talent', and the use of the word 'modern' rather than 'new' in the title of The Faber Book of Modern Verse made it sound just a little different and also avoided the word 'modernist', which Eliot disliked in the context of poetry, yet still suggested a distinctive up-to-dateness
Miss Nancy Ellicott smoked
And danced all the modern dances;
And her aunts were not quite sure how they
felt about it,
But they knew that it was modern.