From Scots/English 'laddie' meaning 'young boy'; used as a given name for both sexes.
Laddie derives from the Scottish and Northern English word *lad*, itself tracing to Middle English *ladde*, a term for a young man or boy of uncertain further etymology — possibly from Old Norse or simply a native formation. As a given name, Laddie represents the charming linguistic phenomenon of affectionate colloquialisms crystallizing into proper names, the same impulse that turned "bonny" and "bairn" into regional endearments capable of standing on a birth certificate. In Scotland and the Scottish diaspora communities of Canada, Australia, and the American Midwest, Laddie was occasionally bestowed as a genuine first name, particularly in the late nineteenth and early twentieth centuries.
It also became a beloved name for dogs — most famously the loyal rough collies of literature and film — which has given the name a dual life in the cultural imagination. The fictional Lassie's companion, and countless barn collies named Laddie across generations of farms, wove the name into the fabric of pastoral life. For human bearers, Laddie carries an irrepressible energy: boyish, open-hearted, and slightly roguish in the best sense.
It never quite lost its diminutive quality, which is both its limitation and its appeal. In an era of names straining for gravitas, Laddie offers something rarer — uncomplicated joy.