Both lassie and laddie are reminders of the Viking raids and temporary conquest of parts of Britain in the Dark and early Middle Ages.
Lass began as the Scandinavian word loskr and meant someone light or slight.
Around 1725 the word evolved into lassie, Scottish for an unmarried woman or girl.
To the Vikings, lad was ladde and meant a boy or young man who was led, such as a foot soldier or a male servant.
The word became laddie around 1546.
Extensions to pet and proper names, such as the ie in laddie or lassie, or the y in names like Robby or Donny, surfaced in Scotland around 1400 and became popularized as endearments by the poems of Robert Bums (1759-1796).
