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

(en adjective)

Requiring urgent attention.

* {{quote-magazine, date=2013-06-21, author=(Oliver Burkeman)

, volume=189, issue=2, page=27, magazine=(The Guardian Weekly) , title= The tao of tech , passage=The dirty secret of the internet is that all this distraction and interruption is immensely profitable. Web companies like to boast about "creating compelling content", or offering services that let you "stay up to date with what your friends are doing", "share the things you love with the world" and so on.}}

Forceful.

* {{quote-news, year=2011, date=October 29, author=Phil McNulty, work=BBC Sport

, title= Chelsea 3-5 Arsenal , passage=Terry's goal looked to have put Chelsea in control on the stroke of half-time but Arsenal's response presented a compelling case for Wenger's insistence that reports of his side's demise have been greatly exaggerated.}}