Likely related to Adele or Adela, from Germanic roots meaning 'noble.'
Adeli is a sleek, compressed form of the Old High German name-stock built on the element "adal," meaning "noble" or "of noble kind." This root generated one of medieval Europe's most productive naming families: Adela, Adele, Adelaide, Adelheid, Adeline, and dozens of regional variants. Adeli strips the tradition down to its sonorous core — three syllables with a bright, open ending — sitting somewhere between the formal Adelaide and the French-inflected Adèle.
The -i ending also echoes naming conventions in Basque, Italian, and various Slavic contexts, giving the name a quietly cosmopolitan character. The "adal" prefix was prized in Frankish and Germanic aristocratic culture because it literally encoded lineage and worth into a child's identity. Queens, empresses, and abbesses bore Adelaide and its kin throughout the early medieval period; Saint Adelheid of Burgundy, who became Holy Roman Empress in the tenth century, was one of the most influential women in European history and helped cement the name's prestige for centuries.
Adeli, as a shorter variant, likely arose through the affectionate diminutive habit common to Romance-language speakers shortening longer Germanic names in everyday speech. In contemporary use, Adeli has a crisp, modern feel while remaining etymologically deep. It appears in Spanish-speaking Latin American communities — where the -i ending feels natural and warm — as well as in European contexts where minimalist name aesthetics have become fashionable. It offers parents a name that sounds fresh without being invented, rooted without feeling antique.