Plain, a. [Compar. Plainer; superl. Plainest.]
Etymology: [F., level, flat, fr. L. planus, perhaps akin to E. floor. Cf. Llano, Piano, Plan, Plane level, a level surface.]
1. Without elevations or depressions; flat; level; smooth; even. See Plane. The crooked shall be made straight, and the rough places plain. Isa. xl. 4.
2. Open; clear; unencumbered; equal; fair. Our troops beat an army in plain fight. Felton.
3. Not intricate or difficult; evident; manifest; obvious; clear; unmistakable. "'T is a plain case." Shak.
4. (a) Void of extraneous beauty or ornament; without conspicious embellishment; not rich; simple. (b) Not highly cultivated; unsophisticated; free from show or pretension; simple; natural; homely; common. "Plain yet pious Christians." Hammond. "The plain people." A. Lincoln. (c) Free from affectation or disguise; candid; sincere; artless; honest; frank. "An honest mind, and plain." Shak. (d) Not luxurious; not highly seasoned; simple; as, plain food. (e) Without beauty; not handsome; homely; as, a plain woman. (f) Not variegated, dyed, or figured; as, plain muslin. (g) Not much varied by modulations; as, a plain tune. Plain battle, open battle; pitched battle. [Obs.] Chaucer. -- Plain chant (Mus.) Same as Plain song, below. -- Plain chart (Naut.), a chart laid down on Mercator's projection. -- Plain dealer. (a) One who practices plain dealing. (b) A simpleton. [Obs.] Shak. -- Plain dealing. See under Dealing. -- Plain molding (Join.), molding of which the surfaces are plain figures. -- Plain sewing, sewing of seams by simple and common stitches, in distinct from fancy work, embroidery, etc.; -- distinguished also from designing and fitting garments. -- Plain song. (a) The Gregorian chant, or canto fermo; the prescribed melody of the Roman Catholic service, sung in unison, in tones of equal length, and rarely extending beyond the compass of an octave. (b) A simple melody. -- Plain speaking, plainness or bluntness of speech.
1 more senses
Syn. -- Level; flat; smooth; open; artless; unaffected; undisguised; frank; sincere; honest; candid; ingenuous; unembellished; downright; blunt; clear; simple; distinct; manifest; obvious; apparent. See Manifest.
5 other Webster entries under this spelling
Plain, v. i.
To lament; to bewail; to complain. [Archaic & Poetic] Milton. We with piteous heart unto you pleyne. Chaucer.
Plain, v. t.
To lament; to mourn over; as, to plain a loss. [Archaic & Poetic] Sir J. Harrington.
Plain, adv.
In a plain manner; plainly. "To speak short and pleyn." Chaucer. "To tell you plain." Shak.
Plain, n.
1. Level land; usually, an open field or a broad stretch of land with an even surface, or a surface little varied by inequalities; as, the plain of Jordan; the American plains, or prairies. Descending fro the mountain into playn. Chaucer. Him the Ammonite Worshiped in Rabba and her watery plain. Milton.
2. A field of battle. [Obs.] Arbuthnot. Lead forth my soldiers to the plain. Shak.
Plain, v. t. [imp. & p. p. Plained (; p. pr. & vb. n. Plaining.]
1. To plane or level; to make plain or even on the surface. [R.] We would rake Europe rather, plain the East. Wither.
2. To make plain or manifest; to explain. What's dumb in show, I'll plain in speech. Shak.
Shades of meaning
Fernald has no entry of its own for plain; he lists it under clear, evident, horizontal, rustic.
Where he writes about it:
That is plain, in the sense here considered, which is, as it were, level to the thought, so that one goes straight on without difficulty or hindrance; as, plain language; a plain statement; a clear explanation. — from clear
Perspicuous is often equivalent to plain, but plain never wholly loses the meaning of unadorned, so that we can say the style is perspicuous tho highly ornate, when we could not call it at once ornate and plain. — from clear
The adjective plain, originally the same word as plane, is now rarely used except in the figurative senses, but the original sense appears in the noun, as we speak of "a wide plain." We speak of a horizontal line, a flat morass, a level road, a plain country, a plane surface (especially in the scientific sense). — from horizontal