Informal diminutive of 'son,' used as an affectionate name meaning 'little son' or 'young boy.'
Sonnie is a variant spelling of Sonny, a name that functions as both an endearment and a given name with genuine warmth at its core. As a term of address, *sonny* has been used in English since at least the mid-nineteenth century, a diminutive of *son* used affectionately for a boy or young man — a verbal equivalent of a hair tousle. When it migrated into use as a formal given name, it brought all that affection with it, a name that implies a child beloved from the moment of naming.
The spelling Sonnie gives the name a slightly more formal look on paper while preserving the identical sound — a common practice in the early twentieth century when parents wanted endearment names to carry better on a birth certificate or job application. Notable bearers include Sonnie Hale, the British comedian and film director who was a major figure in 1930s British entertainment, married to Jessie Matthews. The name also resonates through jazz and blues culture, where *Sonny* (in its various spellings) appears on some of the most celebrated musicians of the twentieth century — Sonny Rollins, Sonny Boy Williamson, Sonny Liston.
Sonnie can also carry a sunnier reading — a phonetic link to *sunny*, warm and bright, that makes it feel like a forecast for a child's disposition. In an era when short, joyful names are genuinely fashionable again (think Sunny, Beau, Rue), Sonnie offers something slightly vintage and personal, a name that feels like a nickname someone earned through being deeply loved.