Adjective

(en adjective)

Well grounded or justifiable, pertinent.

*{{quote-magazine, year=2012, month=March-April

, author=(Jan Sapp) , title=Race Finished , volume=100, issue=2, page=164 , magazine=(American Scientist) citation , passage=Few concepts are as emotionally charged as that of race. The word conjures up a mixture of associations—culture, ethnicity, genetics, subjugation, exclusion and persecution. But is the tragic history of efforts to define groups of people by race really a matter of the misuse of science, the abuse of a valid biological concept?}}

I will believe him as soon as he offers a valid answer.

Acceptable, proper or correct.

A valid format for the date is MM/DD/YY.

Do not drive without a valid license.

Related to the current topic, or presented within context, relevant.

(logic) Of a formula or system: such that it evaluates to true regardless of the input values.

(logic) Of an argument: whose conclusion is always true whenever its premises are true.

An argument is valid if and only if the set consisting of both (1) all of its premises and (2) the contradictory of its conclusion is inconsistent.

Adjective

(er)

Of large size or extent; great; extensive; hence, relatively great; greatest; chief; principal.

a grand mountain

a grand army

a grand mistake

Great in size, and fine or imposing in appearance or impression; illustrious, dignified, or noble (said of persons); majestic, splendid, magnificent, or sublime (said of things).

a grand monarch

a grand view

a grand conception

Having higher rank or more dignity, size, or importance than other persons or things of the same name.

a grand lodge

a grand vizier

a grand piano

Standing in the second or some more remote degree of parentage or descent -- generally used in composition; as, grandfather, grandson, grandchild, etc.

(Ireland, Northern England) fine; lovely