Blackadder

English

WOTD – 15 June 2025

PIE word
*wasdʰos

From black + a second element, possibly derived from one of the following:

From Irish fad (“length”), fada (“long”, adjective) (ultimately from Proto-Indo-European *wasdʰos (“long; wide”)) + dobhar (“moisture; sea; water”) (ultimately from Proto-Indo-European *dʰewbʰ- (“deep”)),^[1] referring to a long river.
From Old English ǣdre (“channel for liquids; river; (anatomy) artery or vein; sinew”), from Proto-Germanic *ēþrǭ (“rivulet; (anatomy) vein”), possibly from Proto-Indo-European *h₁éh₁t-r̥ ~ *h₁h₁t-éns (“lung; internal organ”), from *h₁eh₁t- (“breath; to breathe”) +‎ *-r̥ (suffix forming nouns). However, this etymology has been doubted as it has been suggested that the long initial vowel in Old English would have been preserved in English and Scots.^[2]
From Proto-Brythonic *ador or *edir (“(possibly) name of a river”), possibly ultimately from Proto-Indo-European *hₐet- (“to go”) + *-r̥.^[2]

The surname is from the river and the adjacent Blackadder House.

Blackadder

Preceded by the: A river in the Scottish Borders council area, Scotland, a tributary of Whiteadder Water; in full, Blackadder Water.
A rural locality in the Scottish Borders council area, south of the river (OS grid reference NT8452).
A surname.

^ Compare James B. Johnston (1892) “Adder, Black and White”, in Place-names of Scotland, Edinburgh: David Douglas, →OCLC, page 7.
↑ ^2.0 ^2.1 Alan G. James (2019) “*ador or *edir (f?)”, in The Brittonic Language in the Old North: A Guide to the Place-name Evidence‎^[1], volume 2 (Guide to the Elements), Scottish Place-Name Society, archived from the original on 14 April 2025, page 6.