To substantiate is to give support to a claim. We’d really like to believe in the Tooth Fairy; however, more evidence is needed to substantiate her existence (besides that quarter in your pocket).

Substantiate is related to the word substantial, which means "solid." So, to substantiate a claim is to make it solid or believable. If the evidence given in support of an argument is weak and unconvincing, that evidence can be described as insubstantial. Of course, in special cases like the Tooth Fairy, having substantial evidence doesn’t seem to matter; fans just keep on believing.

Definitions of substantiate

v establish or strengthen as with new evidence or facts

affirm, confirm, corroborate, support, sustain
contradict, negate
prove negative; show to be false
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back, back up
establish as valid or genuine
give supporting evidence
confirm the truth of
demonstrate, establish, prove, shew, show
establish the validity of something, as by an example, explanation or experiment
support or supply with references
prove valid; show or confirm the validity of something
check, check off, mark, mark off, tick, tick off
put a check mark on or near or next to
ascertain, assure, check, control, ensure, insure, see, see to it
be careful or certain to do something; make certain of something
verify by consulting a source or authority
prove oneself
show one's ability or courage
prove formally; demonstrate by a mathematical, formal proof
specify the origin of
contradict, negate
prove negative; show to be false
prove to be of unsound mind or demonstrate someone's incompetence

v represent in bodily form

“The painting substantiates the feelings of the artist”
body forth, embody, incarnate
Type of:
have the quality of being; (copula, used with an adjective or a predicate noun)

v solidify, firm, or strengthen

“The president's trip will substantiate good relations with the former enemy country”
Type of:
beef up, fortify, strengthen
make strong or stronger

v make real or concrete; give reality or substance to

“our ideas must be substantiated into actions”
actualise, actualize, realise, realize
make concrete and real
manifest the effects of (a gene or genetic trait)
Type of:
create, make
make or cause to be or to become

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