There are a lot of names out there that sound like they are the same, but actually have different sources. Today's example:
Cecilia, Celia and Cecil
All three of these names are Latin in origin, but people often think that Celia is a short form of Cecilia, often to the point where Cecilia is often spelled Cecelia.
Cecilia is a feminine form of the Latin name Caecilius, which means "blind."
Celia is a feminine form of Caelus, which was introduced to English by William Shakespeare for his play As You Like It. It stems from the word caelum, meaning "heaven."
Cecil, in modern use, comes from an anglicization of the Welsh name Sesyllt, which comes from the Latin name Sextilius, meaning "sixth." There are a lot of Latin names that are ordinal numbers:
Primus (still used in its Italian form, Primo)
Quintinus/Quintus (still used in an Anglicised French form-- Quentin)
Nonus (the feminine form, Nona is still occasionally heard today)