Synonym of know-it-all / A highly knowledgeable person; expert.

(historical) A member of a secret antiforeigner political organization in the nineteenth-century United States.

(historical) The doctrines, principles, or practices of the Know-Nothings.

Someone who does not give a definite opinion in a questionnaire / Something one is uncertain about.

plural of Know-Nothing

The state of knowing nothing; ignorance. / A perverse admiration or embrace of ignorance.

Used to indicate that the response is probably no, but that the speaker is not entirely certain.

(informal) To be acquainted with the normal process or procedure of a given activity or situation; to be familiar with how something is done.

(idiomatic) To ask (used as a dialogue marker or introductory statement).

In something's current form, which is familiar to the speaker and listener.