Diminutive of Jack or Jacqueline, ultimately from Hebrew Jacob meaning 'supplanter.'
Jacky travels a long road from ancient Hebrew to a breezy English nickname. Its root is John — from Yochanan, meaning God is gracious — which filtered through Latin as Iohannes, became Jankin and Jackin in medieval English, and eventually crystallized into Jack as a standalone name. Jacky emerged as one of several affectionate variants, used for both boys and girls, lending the name a casual warmth that its formal ancestors lack.
As a feminine name, Jacky sits alongside Jackie and Jacqui as diminutives of Jacqueline, itself the French feminine of Jacques (James). The most culturally resonant Jackie of the twentieth century is of course Jacqueline Kennedy Onassis, whose poise during the 1963 assassination and subsequent life of restrained public dignity turned the nickname into a byword for elegance under pressure. The spelling Jacky signals a slightly more tomboyish or informal register, popular mid-century in Britain and Australia where -y endings on names felt approachable and friendly.
For boys, Jacky carries echoes of Jacky Fisher, the controversial First Sea Lord who modernized the Royal Navy before the First World War, and of various folk and blues traditions where Jack-names signified a resourceful everyman. Today Jacky occupies a nostalgic, vintage-cool space — neither common enough to feel generic nor rare enough to feel invented. It rewards a child who wants a name that feels inherited and lived-in rather than freshly minted.