seldom

From late Middle English seldom, alteration of earlier selden by analogy with adverbial datives such as whilom, from Old English seldan (“seldom”), from Proto-West Germanic *seldanā, from Proto-Germanic *seldanē.

Cognate with Saterland Frisian säilden (“seldom”), West Frisian selden, komselden (“rare, seldom”), Dutch zelden, German selten, Danish sjælden, Norwegian Bokmål sjelden, Norwegian Nynorsk sjeldan, Swedish sällan, Faroese sjáldan, Icelandic sjaldan. More at seld and selly.