lowbrow n.

"not high, below the usual level," late 13c., earlier lah (late 12c.), "not rising much, being near the base or ground" (of objects or persons), also "lying on the ground or in a deep place" (late 13c.). This is not found in Old English, so the word is probably from Old Norse lagr "low, low-down, short; humble," or a similar Scandinavian source (compare Swedish låg, Danish lav), from Proto-Germanic *lega- "lying flat, low" (source also of Old Frisian lech, Middle Dutch lage, Dutch laag "low," dialectal German läge "flat"), from PIE root *legh- "to lie down, lay."

In reference to sounds, "not loud," also "having a deep pitch," from c. 1300. Meaning "humble in rank" is from c. 1200; "undignified, not high in character" is from 1550s; meaning "coarse, vulgar" is from 1759. Sense of "dejected, dispirited" is attested from 1737. Of prices, from c. 1400. In geographical usage, low refers to the part of a country near the sea-shore (c. 1300), as in Low Countries "Holland, Belgium, Luxembourg" (1540s). Low German languages (1845) are so called for being spoken in the lower elevations of old Germany.

Abject, low, and mean may have essentially the same meaning, but low is more often used with respect to nature, condition, or rank: mean, to character or conduct: abject, to spirit. [Century Dictionary, 1897]

Low blow in the figurative sense (1940s) is from pugilism. To lie low is from mid-13c. as "get down so as not to be seen," 1880 in the modern slang sense "keep quiet." Low Church in 18c. English history referred to Anglicans laying little stress on church authority (1702); in 19c. it meant evangelical Anglicans.

c. 1300, broue, plural broues, brouen, "arch of hair over the eye," also extended to the prominent ridge over the eye (early 14c.), from Old English bru (plural brua), which probably originally meant "eyebrow" (but also was used in the sense of "eyelash"), from Proto-Germanic *brus- "eyebrow" (source also of Old Norse brun), from PIE *bhru- "eyebrow" (source also of Sanskrit bhrus "eyebrow," Greek ophrys, Old Church Slavonic bruvi, Lithuanian bruvis "brow," Old Irish bru "edge"). The -n- in the Old Norse (brun) and German (braune) forms of the word are from a genitive plural inflection.

The sense was extended by c. 1200 to "the forehead," especially with reference to movements and expressions that showed emotion or attitude, hence "general expression of the face" (1590s). From c. 1400 as "the slope of a steep place."

Words for "eyelid," "eyelash," and "eyebrow" changed about maddeningly in Old and Middle English (and in all the West Germanic languages). The extension of Old English bru to "eyelash," and later "eyelid" presumably was by association of the hair of the eyebrow with the hair of the eyelid. The eyebrows then became Old English oferbrua "overbrows" (early Middle English uvere breyhes or briges aboue þe eiges). The general word for "eyebrow" in Middle English was brew, breowen (c. 1200), from Old English bræw (West Saxon), *brew (Anglian), from Proto-Germanic *bræwi- "blinker, twinkler" (source also of Old Frisian bre, Old Saxon brawa, Middle Dutch brauwe "eyelid," Old High German brawa "eyebrow," Old Norse bra "eyebrow," Gothic brahw "twinkle, blink," in phrase in brahwa augins "in the twinkling of an eye").