drearisome

Old English dreorig "sad, sorrowful," originally "cruel, bloody, blood-stained," from dreor "gore, blood," from (ge)dreosan (past participle droren) "fall, decline, fail," from West Germanic *dreuzas (cf. Old Norse dreyrigr "gory, bloody," and more remotely, German traurig "sad, sorrowful"), from PIE root *dhreu- "to fall, flow, drip, droop" (see drip (v.)).

The word has lost its original sense of "dripping blood." Sense of "dismal, gloomy" first recorded 1667 in "Paradise Lost," but Old English had a related verb drysmian "become gloomy."