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)

Worthy of esteem; admirable.

* 1868 , , Little Women , ch. 22,

Mr. March told . . . how devoted Brooke had been, and how he was altogether a most estimable and upright young man.

(archaic) Valuable.

* 1596 , , The Merchant of Venice , act 1, scene 3:

A pound of man's flesh taken from a man

Is not so estimable , profitable neither,

As flesh of muttons, beefs, or goats.

Capable of being estimated.

* 1928 , Louis Kahlenberg and Norbert Barwasser, "On the time of Absorption and Excretion of Boric Acid in Man," Journal of Biological Chemistry , volume 79, iss. 2, page 406:

After this time boric acid is always present in estimable amounts.