Cailean

Colin (sometimes spelled Collin) is a male given name. Colin is usually pronounced KO-lin, although some (primarily in the US) use KOH-lin.
Like many given names, it has multiple origins, including:
an Anglicized form of the Gaelic name "Cailean" or "Coileáin", meaning "whelp", "cub", or "young pup";
a diminutive form of Nicolas (before the 17th century in England, most nicknames had the diminutive ending "in" or "Kin", where the ending is attached to the first syllable, a few remain such as Robin (Rob-in, from Robert), Hank (Hen-Kin from Henry), Jack (Jan-kin from John), and Colin (Col-in from Nicolas);
a diminutive form of "Colle", a short French form of Nicholas (Greek), meaning "victorious people";
a development of the Norse name "Koli", meaning "dark", a Middle English surname given to those living on property whose ownership was disputed;
In the UK and Ireland, the name is spelt with one "L", Colin; in the US, it is sometimes spelt with two, Collin. It ranked 319th most popular name England and Wales in 1996 and 684th most popular in 2014. It has been moderately popular in the United States and was listed in the top 100 boys names in the U.S. in 2005. In Scotland it ranked 302 in 2014, but in Ireland it is more popular, ranking 88th in 2006. Collin is slowly becoming more popular in the US, making the top 100 boys' names in each of the three years to 2005, with Colin being slightly less popular. In total, the two spellings accounted for around 1 in 300 boys named in the US in 2005.

Means: whelp, young dog, child in Scottish Gaelic.