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)

Evincing strength; indicating vigorous health; strong; sinewy; muscular; vigorous; sound; as, a robust body; robust youth; robust health.

He was a robust man of six feet four.

* Anthony Trollope (1815-1882)

She was stronger, larger, more robust physically than he had hitherto conceived.

Violent; rough; rude.

* {{quote-news

, year=2011 , date=October 1 , author=Phil McNulty , title=Everton 0 - 2 Liverpool , work=BBC Sport citation , page= , passage=As a frenetic opening continued, Cahill - whose robust approach had already prompted Jamie Carragher to register his displeasure to Atkinson - rose above the Liverpool defence to force keeper Pepe Reina into an athletic tip over the top.}}

Requiring strength or vigor; as, robust employment.

Sensible (of intellect etc.); straightforward, not given to or confused by uncertainty or subtlety;

(systems engineering) Designed or evolved in such a way as to be resistant to total failure despite partial damage.

(software engineering) Resistant or impervious to failure regardless of user input or unexpected conditions.

(statistics) Not greatly influenced by errors in assumptions about the distribution of sample errors.