drearyyoudaoicibaDictYouDict[dreary 词源字典]
dreary: [OE] In Old English, dreary (or drēorig, as it then was) meant ‘dripping with blood, gory’, but its etymological connections are with ‘dripping, falling’ rather than with ‘blood’. It goes back to a West Germanic base *dreuz-, *drauz- which also produced Old English drēosna ‘drop, fall’, probably the ultimate source of drizzle [16] and drowsy.

The literal sense ‘bloody’ disappeared before the end of the Old English period in the face of successive metaphorical extensions: ‘dire, horrid’; ‘sad’ (echoed in the related German traurig ‘sad’); and, in the 17th century, the main modern sense ‘gloomy, dull’. Drear is a conscious archaism, created from dreary in the 17th century.

=> drizzle, drowsy[dreary etymology, dreary origin, 英语词源]
dreary (adj.)youdaoicibaDictYouDict
Old English dreorig "sad, sorrowful," originally "cruel, bloody, blood-stained," from dreor "gore, blood," from (ge)dreosan (past participle droren) "fall, decline, fail," from Proto-Germanic *dreuzas (cognates: 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."