bleakyoudaoicibaDictYouDict[bleak 词源字典]
bleak: [16] Bleak originally meant ‘pale’, and comes ultimately from an Indo-European base *bhleg-, possible source of black and a variant of *phleg-, which produced Greek phlégein ‘burn’ and Latin flagrāre ‘burn’ (whence English conflagration and flagrant; flame, fulminate, and refulgent are also closely related).

From *bhlegcame the prehistoric Germanic adjective *blaikos ‘white’, from which Old English got blāc ‘pale’ (the sense relationship, as with the possibly related blaze, is between ‘burning’, ‘shining brightly’, ‘white’, and ‘pale’). This survived until the 15th century in southern English dialects as bloke, and until the 16th century in the North as blake.

Its disappearance was no doubt hastened by its resemblance to black, both formally and semantically, since both ‘pale’ and ‘dark’ carry implications of colourlessness. Blake did however persist in Northern dialects until modern times in the sense ‘yellow’. Meanwhile, around the middle of the 16th century bleak had begun to put in an appearance, borrowed from a close relative of bloke/blake, Old Norse bleikr ‘shining, white’.

The modern sense ‘bare’ is recorded from very early on. A derivative of the Germanic base *blaikwas the verb *blaikjōn, source of Old English blǣcan ‘whiten’, the ancestor of modern English bleach (which may be related to blight). And a nasalized version of the stem may have produced blink [14].
=> bleach, blight, blink, conflagration, flagrant, flame, fulminate[bleak etymology, bleak origin, 英语词源]
bleak (adj.)youdaoicibaDictYouDict
c. 1300, "pale," from Old Norse bleikr "pale, whitish, blond," from Proto-Germanic *blaika- "shining, white," from PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)). Later "bare, windswept" (1530s). Sense of "cheerless" is c. 1719 figurative extension. The same Germanic root produced Old English blac "pale," but this died out, probably from confusion with blæc "black;" however bleak persisted, with a sense of "bare" as well as "pale."