Emily Dickinson Lexicon

PLAIN, a. [Fr. plain; It. piano; Sp. plano, llano; Port. plano; from L. planus; G. and Sw. plan; D. plein; Sw. Dan. D. and G. plan, a plan or scheme; W. plan, a plane, a plantation, a shoot or cion, a ray of light, whence plant, children, issue; pleiniaw, to radiate; plenig, radiant, splendid, whence ysplan, clear, bright, splendid, and ysplander, L. splendor. The Gr. πλαναω, to wander, is from the same root. Here we have decisive evidence, that plain, plan, plant, and splendor, are from the same radix. See Plant. Class Ln, No. 4, 6, 7.]

1. Smooth; even; level; flat; without elevations and depressions; not rough; as, plain ground or land; a plain surface. In this sense, in philosophical writings, it is written plane.
2. Open; clear. Our troops beat an army in plain fight and open field. – Felton.
3. Void of ornament; simple; as, a plain dress. Plain without pomp, and rich without a show. – Dryden.
4. Artless; simple; unlearned; without disguise, cunning or affectation; without refinement; as, men of the plainer sort. – Gen. xxv. Bacon. Plain, but pious Christians. Hammond.
5. Artless; simple; unaffected; unembellished; as, a plain tale or narration.
6. Honestly undisguised; open; frank; sincere; unreserved. I will tell you the plain truth. Give me leave to be plain with you. – Bacon.
7. Mere; bare; as, a plain knave or fool. – Shak. Pope.
8. Evident to the understanding; clear; manifest; not obscure; as, plain words or language; a plain difference; a plain argument. It is plain in the history, that Esau was never subject to Jacob. – Locke.
9. Not much varied by modulations; as, a plain song or tune.
10. Not high seasoned; not rich; not luxuriously dressed; as, a plain diet.
11. Not ornamented with figures; as, plain muslin.
12. Not dyed.
13. Not difficult; not embarrassing; as, a plain case in law.
14. Easily seen or discovered; not obscure or difficult to be found; as, a plain road or path. Our course is very plain. – Ps. xxvii. A plain or plane figure, in geometry, is a uniform surface, from every point of whose perimeter right lines may be drawn to every other point in the same. – Encyc. A plain figure, in geometry, is a surface in which, if any two points are taken, the straight line which joins them lies wholly in that surface. A plain angle, is one contained under two lines or surfaces, in contradistinction to a solid angle. – Encyc. A horizontal plain is parallel to the horizon. An inclined plain is any plain inclined to the horizon, by whatever angle.