(a) Flat, level, even; of geographic areas: low in elevation, lowland; broad, flat; also, of an engraving: worked in low relief; ~ contre (ground, place, thing), a plain, plateau, or lowland plain; (b) maken ~, to raze (a city, castle, etc.); also, make (sth.) level or even; planir and as ~ as a ~ table, as flat as flat can be; from (of) the ~ erthe, from ground level, off the ground; upon the ~ erthe, flat on the ground; all the ~ world, the whole wide world; (c) of a field, pasture, path, etc.: bare, open, free of obstructions; cleared, prepared for sowing; also, free of people; also, of the sea: unobstructed by rocks; ~ place, a clearing, an open space; ~ contre, land which is not built up, rural country [quot.: c1436]; ~ lond, unfortified land [quot.: Mannyng 4821]; (d) of a street or path: easily traversed, open, public; of a field of battle or lists for jousting: open, clear; (e) comp. adj. plainer as noun: a plain, lowland, valley.

(a) Smooth, even surfaced; of bed clothes; undisturbed; also fig.; ~ as a line; plat and ~; maken ~, to polish (sth.), make (sth.) smooth; (b) of the body or a part of the body: smooth, unwrinkled; also, hairless, bald; of the face: flat, without prominent features; of hair: straight, not curled; of a bird: with unruffled feathers; (c) anat. flat or smooth; surg. of a wound: smooth, clean, without rough edges or bone splinters; of a splint, surgical instrument, etc.: smooth, flat, plain, without lateral projections or rough edges; pathol. of an infection: smooth, not eruptive or scabby; also, simple, without complications; (d) of the sea, a lake, or the air: calm, smooth, even, gentle; (e) gon ~ pas, wenden with pas ful ~, to go directly or straightway; ~ wei, a direct path.

Geom. Confined to two dimensions, as it were on a flat surface without depth; ~ figure, a figure having but two dimensions; ~ mesure, the measure of length or width.

(a) Plain, simple, unadorned; also, stripped of valuables, bare; of clothes: unembellished; also, without padding; (b) plainly woven, not twilled; ~ cloth, a fabric without twill, design, or embroidery; (c) without armor; in ~ armes; (d) common, ordinary, usual; also, modest, lowly [quot.: a1420]; also, not intimate or overly familiar [quot.: a1450]; (e) mus. monophonic as opposed to polyphonic; in plainsong.

(a) Clear, explicit; unambiguous, unmistakable; also, evident, overt; (b) of a planet's orbit: fixed; (c) of a gem: clear, transparent, or translucent; (d) free from deception or distortion; actual, real, true; ~ account; ~ cas (mening, soth, treuth); (e) of persons, the heart, the will: candid, honest, sincere, truthful; reliable, dependable; open, frank, forthright; of the countenance: having a sincere expression or an honest appearance; hole and ~; ~ conscience, a clear conscience; ~ withouten gile (ipocrisie); (f) simple, pure, absolute; paradise ful ~, ?utter paradise; (g) as noun: at ~, in (short and) ~, plainly; the ~, the plain case; the short and ~, the long and the short of it, briefly, concisely.

Of words, language, speech, or narrative: (a) clear, unambiguous; truthful, direct, to the point; of one's manner of speaking: sincere; plat and ~; ~ English; ~ langage; (b) not embellished by the figures of rhetoric, simple, ordinary, unaffected.