Adjective

(en-adj)

Having, or capable of exerting power, potency or influence.

* (William Shakespeare)

The powerful grace that lies / In herbs, plants, stones, and their true qualities.

*{{quote-book, year=1963, author=(Margery Allingham), title=(The China Governess)

, chapter=19 citation , passage=As soon as Julia returned with a constable, Timothy, who was on the point of exhaustion, prepared to give over to him gratefully. The newcomer turned out to be a powerful youngster, fully trained and eager to help, and he stripped off his tunic at once.}}

(mining) Large; capacious; said of veins of ore.

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.