Necessary truth

Necessary truth is a sentence which is true by virtue of its logical structure.

Example
sentence (i) is necessarily true due to the meaning of the logical constants every, or, independently of the words raven and black:

(i) Every raven is black or not black

Sentence (i) is also called a tautology. All sentences that are not necessarily true are contingently true (see contingent truth). See also analytic truth.

Links
Utrecht Lexicon of Linguistics