Elizabeth: an oath, and the island the eels paid for
The eels were rent.
Ely Abbey paid Thorney Abbey 26,275 eels to lease one fen. By Domesday, 1086, England owed somewhere over half a million eels a year in rent, counted in sticks of 25. The fish that named the island paid for it. Elizabeth asked that strangers meet the fish before they meet her, so the fish go first.
Two halves, both older than the country.
Elizabeth. Hebrew אֱלִישֶׁבַע, Elisheva. El, God; shava', to swear, to bind with an oath. “My God is an oath.” It shows up in the Hebrew Bible as Aaron's wife (Exodus 6:23), then in Luke's Greek as Elisabet, mother of John the Baptist, then through Latin as Elizabeth. The oath in it is the swearing, not the keeping. The name marks the moment you bind yourself. It says nothing about whether you held.
Ely is a real island in the Fens. Old English ēl, eel, plus ēg/gē, island or district. The eel-isle. Bede is the first to write the reading down. Water on every side until the Fens were drained in the 1600s. That water made it a fortress: Hereward the Wake held it against William the Conqueror after 1066, until the monks sold him out.
The surname is habitational, from the place. Earliest spelling I found: Huna de Ely, 1086. Some Elys come instead from Elie, from Elijah. A different road. I can't tell you which one you are without a paper trail, and I won't invent one.
So the name, plainly: an oath, on an island that water defended and men drained. The surname is a place you can't get back to because it stopped being a place. That's not me being clever. The map did it.
Sources: Wikipedia (Elizabeth given name; Isle of Ely); Univ. of Iowa Bible & Archaeology (Elisheba); Historic UK (Ely); SurnameDB and Geneanet (Ely surname); Atlas Obscura and HistoryExtra (eel rents); Medieval Histories (sticks of 25).
Commissioned by Elizabeth Ely, who asked for it traced, not flattered. Published with her permission. Her own door, where she walks places you can't get back to: paper.wf/elizabeth-ely. First look free; the paid desk sits under the fold.
A name, traced: one page on one name, where it comes from and what it has carried. Sources checked. Send one: [email protected]. First look free.