My mother, acting upon a blessed inspiration, decided to name me Declan (after St. Declan, the 5th century missionary to Ireland, and Bishop of Ardmore, whose feast falls on July 24th). Declan is the anglicised form of Deaglán or Déaglán (I have seen also Déagláinn). There is another St. Declan, a 8th century Irish missionary to Germany (whose memorial is December 1st). The name in its anglicised form is usually pronounced 'Declun', or 'Decklin' in Ireland and anywhere else in the 'Anglosphere'. That ravishing French girl of your acquaintance will insist on 'DéCLAN' (rhymes with Jean), and you should simply beam at her. But be prepared - especially if you are the only person of the name in a foreign country - for confrontation with a truly bewildering variety of other well-meaning mispronunciations. My personal experience of these has included 'DIGlan', 'DAHNKlan', 'DAYklan', 'Decland', 'Decklennn' and one or two versions with a duck in them somewhere. If you use one of the Irish spellings, then may God and St. Declan help you. I have personally noticed its occurrence very gradually becoming more frequent outside Ireland (in the media) since the late 1980s, so it may now offer less of a challenge. In my case, it has been 'Dec' for short, and occasionally 'Dex' in business contexts.It appears to be correct that no meaning is known officially, but it has traditionally been said to be 'man of prayer'. This is the one I was told, and I can think of no reason to find it objectionable. Se non è vero, è ben trovato.The name Declan, in any spelling, is, of course, among the finest and best ever to have been given on this earth since the giving of names began. Bear it proudly! And God bless those mothers who have chosen it for their boys. A note of warning, though: in agreement with several good lady commentators above, I have to say little Declans may indeed be troublemakers. I can still hear my own mother, Lord rest her soul, saying "You could start a mutiny in Heaven!" Our mothers are often unsettlingly right about many things, ourselves included. I have reached the point where I can admit it: I was a very bold child, for quite a while - the kind whose mother could not take anywhere. There was trouble at the Mass, dreadful trouble at the Post Office (with a floor that made it easy to whizz over from the entrance to the enticing waste paper basket with all the discarded sticky bits from books of stamps). Trouble seemed not merely my business, but my manifest destiny! It is a wonder I didn't end up living in Carlotta... I'm really, really nice now, though.