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)

Proven; shown to be true with evidence

Supported with testimony

Certified as good, correct, or pure

* 1599 , , First Folio edition, Act V, Scene 1:

A Contract of eternall bond of loue,

Confirm'd by mutuall ioynder of your hands,

Atte?ted by the holy clo?e of lippes,

(linguistics) Of words or languages, proven to have existed by records.

*

A term should be included if it's likely that someone would run accross it and want to know what it means. This in turn leads to the somewhat more formal guideline of including a term if it is attested' and ' idiomatic .

* The word slæpwerig'' (sleep-weary) is attested in the Exeter Book in the form ''slæpwerigne .