substantial vs solid

substantial is not a noun while solid is a noun.

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

As adjectives, substantial and solid are synonyms defined as:

Other synonyms of substantial include strong.

As adjectives, substantial and solid are synonyms defined as:

Other synonyms of substantial include hearty, satisfying, square.

substantial (noun)	solid (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

substantial (adjective)	solid (adjective)
having substance or capable of being treated as fact; not imaginary	of definite shape and volume; firm; neither liquid nor gaseous
of considerable importance, size, or worth	entirely of one substance with no holes inside
of or relating to the real nature or essential elements of something	having length, breadth and thickness
having an abundant supply of money or possessions of value	characterized by good substantial quality
of good quality and condition; solidly built	not soft or yielding to pressure
providing abundant nourishment	of one substance or character throughout
	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