Plain Plain, v. t. [imp. & p. p. {Plained}; p. pr. & vb. n. {Plaining}.] [Cf. {Plane}, v.] 1. To plane or level; to make plain or even on the surface. [R.] [1913 Webster]

We would rake Europe rather, plain the East. --Wither. [1913 Webster]

2. To make plain or manifest; to explain. [1913 Webster]

What's dumb in show, I'll plain in speech. --Shak. [1913 Webster]

The Collaborative International Dictionary of English. 2000.