Solid

a. [Lat. solidus, from solum, the bottom, ground; It. & Sp. solido, Fr. solide.]

1. Having the constituent parts so firmly adhering as to resist the impression or penetration of other bodies; hard; firm; compact;—opposed to fluid and liquid, or to plastic, like clay, or to incompact, like sand.
2. Not hollow; full of matter; as, a solid globe or cone, as distinguished from a hollow one; not spongy; dense; hence sometimes, heavy.
3. Having all the geometrical dimensions; cubic; as, a solid foot contains 1728 solid inches.

☞ In this sense, cubic is now generally used.

4. Firm; compact; strong; as, a solid pier; a solid pile; a solid wall.
5. Worthy of credit, trust, or esteem; substantial, as opposed to frivolous or fallacious; weighty; firm; strong; valid; just. “The solid purpose of a sincere and virtuous answer.” Milton.

These, wanting wit, affect gravity, and go by the name of solid men. Dryden.

6. Sound; not weakly; as, a solid constitution of body. [Rare.] Watts.
7. (Bot.) Of a fleshy, uniform, undivided substance, as a bulb or root; not spongy or hollow within, as a stem.
8. (Metaph.) Impenetrable; resisting or excluding any other material particle or atom from any given portion of space;—applied to the supposed ultimate particles of matter.

Solid angle (Geom.), an angle formed by three or more plane angles, which are not in the same plane, meeting in a point.—Solid measure, a measure for volumes, in which the units are each a cube of fixed linear magnitude, as a cubic foot, yard, or the like; thus, a foot, in solid measure, or a solid foot, contains 1728 solid inches.—Solid newel (Arch.), a newel into which the ends of the stairs are built, in distinction from a hollow newel. See HOLLOW, a.—Solid problem (Geom.), a problem which can be construed geometrically only by the intersection of a circle and a conic section, or of two conic sections. Hutton.—Solid square (Mil.), a square body of troops; a body in which the ranks and files are equal. Syn.—Hard; firm; compact; strong; substantial; stable; sound; real; valid; true; just; weighty; profound; grave; important.—SOLID, HARD. These words both relate to the internal constitution of bodies; but hard denotes a firmer adherence of the component parts than solid. Hard is opposed to soft, and solid to fluid or liquid. Wood is always solid; but some kinds of wood are hard, and others are soft. Repose you there, while I to the hard house, More hard than is the stone whereof ’tis raised. Shak. I hear his thundering voice resound, And tramping feet that shake the solid ground. Dryden.