1. having three dimensions (length, breadth, and thickness), as a geometrical body or figure.
2. of or relating to bodies or figures of three dimensions: solid geometry.
3. having the interior completely filled up, free from cavities, or not hollow: a solid ball of matter.
4. without openings or breaks: a solid wall.
5. firm, hard, or compact in substance: solid ground.
6. having relative firmness, coherence of particles, or persistence of form, where the relative positions of atoms remain fixed, as matter that is not liquid or gaseous: solid particles floating in a liquid.
7. relating to such matter: ice is water in a solid state.
8. dense, thick, or heavy in nature or appearance: solid masses of cloud.
9. substantial, or not flimsy, slight, or light, as buildings, furniture, fabrics, food, etc.
10. of a substantial character; not superficial, trifling, or frivolous: solid learning.
11. undivided or continuous: a solid row of buildings.
12. whole or entire: one solid hour.
13. forming the whole; being the only substance or material: solid gold.
14. uniform in tone or shade, as a colour.
15. real or genuine: solid comfort.
16. sound or good, as reasons, arguments, etc.
17. sober-minded or sensible.
18. financially sound or strong.
19. Obsolete cubic: a solid foot contains 1728 solid inches.
20. having the lines not separated by leads, or having few open spaces, as type or printing.
21. thorough, vigorous, great, big, etc. (with emphatic force, often after good ): a good solid blow.
22. firmly united or consolidated: a solid combination.
23. united in opinion, policy, etc., or unanimous.
24. Colloquial on a friendly, favourable, or advantageous footing.
25. a body or magnitude having three dimensions (length, breadth, and thickness).
26. a solid substance or body; a substance exhibiting rigidity.
27. ( plural ) food that is not in liquid form.
28. an opal which has been cut and polished but not modified in any other way (opposed to doublet, triplet ).
29. a bit solid, Colloquial unreasonable; harsh; severe.
[ME, from L solidus ]
-- solidly, adverb -- solidness, noun