Definition of unusual name is often taken to be less used name, and in 2021 there was 53 babies named Cecily. But there was also 53 babies named Louise and I'm certain most of you will agree Louise isn't really unusual name. They are both listed as rank 709.
Would that make Cecily unusual name? Or do you think, it's familiar, but not popular name?
I would argue Cecily might be counted as unusual name, but I would still describe it as "normal" name. Kind of like Cordelia is unusual, but most people are familiar with the play and although they would not use it, it would not raise too much eyebrows. Do you agree?
full data about names beyond top 100 can be found in these documents https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/livebirths/datasets/babynamesenglandandwalesbabynamesstatisticsgirls