anent (prep.)youdaoicibaDictYouDict
"concerning, about," early 13c., onont "on level with," also "in the company of, fronting against," from Old English on efn "near to, close by," originally "on even (ground) with;" the parasitic -t added 12c. A northern form (in Midlands, anenst, with adverbial genitive), affected by English writers in Scottish sense of "in respect or reference to." Compare German neben "near to, by the side of," short for in eben, from Old High German ebani "equality."
effleurage (n.)youdaoicibaDictYouDict
"gentle rubbing with the palm of the hand," 1886, from French effleurage, from effleurer "to graze, touch lightly, touch upon, strip the leaves off," from ef- "out" (see ex-) + fleur as in the phrase à fleur de "on a level with," from German Flur "a plain, field, meadow" (see floor (n.)).
equal (adj.)youdaoicibaDictYouDict
late 14c., "identical in amount, extent, or portion;" early 15c., "even or smooth of surface," from Latin aequalis "uniform, identical, equal," from aequus "level, even, flat; as tall as, on a level with; friendly, kind, just, fair, equitable, impartial; proportionate; calm, tranquil," which is of unknown origin. Parallel formation egal (from Old French egal) was in use late 14c.-17c. Equal rights is from 1752; by 1854, American English, in relation to men and women. Equal opportunity (adj.) in terms of hiring, etc. is recorded by 1925.
flush (adj.)youdaoicibaDictYouDict
1550s, "perfect, faultless;" c. 1600, "abundantly full," also "full of life or spirit," also "plentifully supplied" (with money, etc.), perhaps from flush (v.1) through the notion of a river running full, hence level with its banks. Meaning "even, level" is from 1620s, originally of ship's decks. In general use by 1791; in typography, 1900; in pugilism, 1812.
slight (adj.)youdaoicibaDictYouDict
early 14c., "flat, smooth; hairless," probably from a Scandinavian source akin to Old Norse slettr "smooth, sleek," from Proto-Germanic *slikhtaz (cognates: Old Saxon slicht; Low German slicht "smooth, plain common;" Old English -sliht "level," attested in eorðslihtes "level with the ground;" Old Frisian sliucht "smooth, slight," Middle Dutch sleht "even, plain," Old High German sleht, Gothic slaihts "smooth"), probably from a collateral form of PIE *sleig- "to smooth, glide, be muddy," from root *(s)lei- "slimy" (see slime (n.)).

Sense evolution probably is from "smooth" (c. 1300), to "slim, slender; of light texture," hence "not good or strong; insubstantial, trifling, inferior, insignificant" (early 14c.). Meaning "small in amount" is from 1520s. Sense of German cognate schlecht developed from "smooth, plain, simple" to "bad, mean, base," and as it did it was replaced in the original senses by schlicht, a back-formation from schlichten "to smooth, to plane," a derivative of schlecht in the old sense [Klein].