Variant of Lily, from Latin 'lilium,' symbolizing purity; also a German pet form of Elisabeth.
Lilli is a trim and elegant variant of Lily and Lillian, sharing their roots in the Latin "lilium" and ultimately the ancient Greek "leirion" — the lily flower, a bloom of extraordinary symbolic weight across virtually every culture that has encountered it. In ancient Sumerian poetry the lily represented sexuality and fertility; in Greek mythology it was sacred to Hera; in Christian Europe it became the emblem of purity and the Virgin Mary; in Chinese culture it symbolizes good luck and a happy union. A name built on that flower carries an enormous freight of cultural meaning compressed into four light letters.
The Lilli spelling in particular carries a Central European and German flavor, reflecting naming traditions in Germany, Austria, and Switzerland where the name has long been at home. Its most celebrated bearer is probably Lilli Palmer — born Maria Lilli Peiser in Posen in 1914 — the German actress who built a distinguished career in Hollywood and European cinema across four decades, appearing opposite Rex Harrison (whom she married), Gary Cooper, and William Holden. Her memoir "Change Lobsters and Dance" (1975) became a literary event in Germany.
There is also Lilli in musical theater history: "Lilli Vanessi" is the name of the sharp-tongued leading lady in Cole Porter's "Kiss Me, Kate" (1948), one of Broadway's most celebrated productions. In contemporary naming culture Lilli occupies a sweet spot: it is immediately legible — everyone knows how to say it — while the doubled final letter gives it visual distinction from the more common Lily and Lilly. It feels both vintage and current, European and universally warm.