solid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of definite shape and volume; not liquid or gaseous.
• adjective Mathematics Of or relating to three-dimensional geometric figures or bodies.
• adjective Firm or compact in substance.
• adjective Not hollowed out.
• adjective Being the same substance or color throughout.
• adjective Having no gaps or breaks; continuous.
• adjective Acting together; unanimous.
• adjective Written without a hyphen or space. For example, the word software is a solid compound.
• adjective Printing Having no leads between the lines.
• adjective Of good quality.
• adjective Substantial; hearty.
• adjective Sound; reliable.
• adjective Financially sound.
• adjective Upstanding or dependable.
• adjective Slang Excellent; first-rate.
• noun A substance having a definite shape and volume; one that is neither liquid nor gaseous.
• noun Mathematics A geometric figure having three dimensions.
• adverb Without a break or opening; completely or continuously.
• adverb As a whole; unanimously.

from The Century Dictionary.

• Of uniform color; self-colored: a pigeon-fanciers' term.
• Resisting flexure; not to be bent without force; capable of tangential stress: said of a kind of material substance. See II., 1.
• Completely filled up; compact; without cavities, pores, or interstices; not hollow: as, a solid ball, as distinguished from a hollow one; solid soda-water, not frothy.
• Firm; strong: as, a solid pier; a solid wall.
• In botany, of a fleshy, uniform, undivided substance, as a bulb or root; not spongy or hollow within, as a stem.
• In anatomy and zoology:
• Hard, compact, or firm in consistency; having no cavities or spongy structure: opposed to spongiose, porous, hollow, cancellate, excavated, etc.
• In entomology, specifically, formed of a single joint, or of several joints so closely applied that they appear to be one: especially said of the capitulum or club of capitate antennæ.
• Having three dimensions; having length, breadth, and thickness; cubic: as, a solid foot contains 1,728 solid inches.
• Sound; not weak; strong.
• Substantial, as opposed to frivolous, fallacious, or the like; worthy of credit, trust, or esteem; not empty or vain; real; true; just; valid; firm; strong; hence, satisfactory: as, solid arguments; solid comfort; solid sense.
• Not light, trifling, or superficial; grave; profound.
• Financially sound or safe; possessing plenty of capital; wealthy; well-established; reliable.
• Unanimous, or practically unanimous: as, a solid vote; the solid South.
• Without break or opening, as a wall or façade.
• Smooth; even; unbroken; unvaried: unshaded: noting a color or pigment.
• Without the liquor, as oysters: said in measuring: opposite to in liquor.
• With reference to fabrics, etc., a uniform color.
• Synonyms Dense.
• Stable, weighty, important.
• noun A body which throughout its mass (and not merely at its surface) resists for an indefinite time a sufficiently small force that tends to alter its equilibrium figure, always springing back into shape after the force is removed; a body possessing elasticity of figure.
• noun In geometry, a body or magnitude which has three dimensions—length, breadth, and thickness—being thus distinguished from a surface, which has but two dimensions, and from a line, which has but one.
• noun plural In anatomy, all parts of the body which are not fluid: as, the solids and fluids of the body.
• noun plural In printing, the parts of an engraving which show black or solid in print.

from the GNU version of the Collaborative International Dictionary of English.

• noun A substance that is held in a fixed form by cohesion among its particles; a substance not fluid.
• noun (Geom.) A magnitude which has length, breadth, and thickness; a part of space bounded on all sides.
• noun (Geom.) See Revolution, n., 5.
• adjective Having the constituent parts so compact, or so firmly adhering, as to resist the impression or penetration of other bodies; having a fixed form; hard; firm; compact; -- opposed to fluid and liquid or to plastic, like clay, or to incompact, like sand.