Alba

Alba is the Scottish Gaelic name (pronounced [ˈal̪ˠapə]) for Scotland. It is cognate with Alba (gen. Albann, dat. Albainn) in Irish and Nalbin in Manx, the two other Goidelic Insular Celtic languages, as well as contemporary words used in Cornish (Alban) and Welsh (Yr Alban), both of which are Brythonic Insular Celtic languages. (The third surviving Brythonic language, Breton, instead uses Bro-Skos, meaning 'country of the Scots'.) In the past these terms were names for Great Britain as a whole, related to the Brythonic name Albion.

The term first appears in classical texts as Ἀλβίων Albíon or Ἀλουΐων Alouíon (in Ptolemy's writings in Greek), and later as Albion in Latin documents. Historically, the term refers to Britain as a whole and is ultimately based on the Indo-European root for "white". It later came to be used by Gaelic speakers in the form of Alba (dative Albainn, genitive Albann, now obsolete) as the name given to the former kingdom of the Picts which when first used in this sense (around the time of king Causantín mac Áeda (Constantine II, 943-952)) had expanded. The region Breadalbane (Bràghad Albann, the upper part of "Alba") takes its name from it as well.

...
Wikipedia