solid vs serious

solid is a noun but serious is not a noun.

Word	Noun	Adjective	Verb	Adverb
solid	Yes	Yes	No	No
serious	No	Yes	No	No

solid (noun)	serious (noun)
a three-dimensional object, structurally rigid, usually resistant to changes of shape or volume
the state in which a substance has no tendency to flow under moderate stress; resists forces (such as compression) that tend to deform it; and retains a definite size and shape
matter that is solid at room temperature and pressure

solid (adjective)	serious (adjective)
of definite shape and volume; firm; neither liquid nor gaseous	concerned with work or important matters rather than play or trivialities
entirely of one substance with no holes inside	completely lacking in playfulness
having length, breadth and thickness	causing fear or anxiety by threatening great harm
characterized by good substantial quality	requiring effort or concentration; complex and not easy to answer or solve
not soft or yielding to pressure	of great consequence
of one substance or character throughout	appealing to the mind
impenetrable for the eye
meriting respect or esteem
of a substantial character and not frivolous or superficial
financially dependable
of good quality and condition; solidly built
uninterrupted in space; having no gaps or breaks
acting together as a single undiversified whole
providing abundant nourishment
of the same color throughout