Adelaide is a name for pet owners who discovered Downton Abbey and never fully recovered. Germanic in origin, from adal (noble) and heid (kind, sort), it's worn by medieval queens and Australian cities, and now by cats and dogs whose owners want something that sounds as though it belongs on a manor house guest register.
The Edwardian Pet Aesthetic
Adelaide fits the old-money, historically-inflected pet naming trend alongside Beatrice, Cordelia, and Clementine. British Shorthairs and Cavalier King Charles Spaniels are natural matches. The name is long for daily use, so expect it to shrink to Addie in practice, which owners are typically fine with.
Human-Pet Crossover
Adelaide has been reviving as a baby name, currently in the US top 200 for girls. The human name Adelaide shares the same dignified, slightly theatrical register. When both human and pet versions climb simultaneously, it signals genuine cultural momentum rather than a passing trend.
Counter-Reading: The Nickname Problem
A four-syllable name on a pet creates an expectation of formality that daily life usually collapses. If you'll actually call the cat Adelaide rather than switching to Addie on day two, this works beautifully. If not, just start with Addie directly.