A lassie is a young girl or woman, especially in Scotland and northern England. When someone calls someone a lassie, they're using a warm, affectionate term that's been part of Scottish culture for centuries.

You might hear a Scottish grandmother say “Come here, lassie” to her granddaughter, or a character in a book set in the Scottish Highlands referring to “a bonnie lassie” (which means a pretty girl). The word carries a friendly, old-fashioned charm. The male equivalent is lad or laddie.

Outside Scotland, many people know the word from Lassie, the famous fictional collie dog from books, movies, and television shows. The original Lassie stories, written by Eric Knight in 1940, featured a loyal, intelligent dog in Yorkshire, England. The name Lassie for the dog probably came from the affectionate Scottish term, suggesting the dog was as beloved as a daughter in her family. Through decades of Lassie stories, the brave collie became one of the most recognizable animal characters in entertainment, always coming to the rescue when people needed help.