1. adjective
Thats a solid plan.
b) Large, massive.
Radioheads on tour! Have you heard their latest album yet? Its quite solid .
2. noun
a) A substance in the fundamental state of matter that retains its size and shape without need of a container (as opposed to a liquid or gas).
I prefer solids over paisleys.
The doctor said I cant eat any solids four hours before the operation.
3. adverb
Without spaces or hyphens.
Many long-established compounds are set solid.
Wikipedia foundation.