IMPROP'ER, adjective [Latin improprius; in and proprius, proper.] 1. Not proper; not suitable; not adapted to its end; unfit; as an improper medicine for a particular disease; an improper regulation. 2. Not becoming; not decent; not suited to the character, time or place; as improper conduct in church; improper behavior before superiors; an improper speech. 3. Not according to the settled usages or principles of a language; as an improper word or phrase. 4. Not suited to a particular place or office; unqualified; as, he is an improper man for the office.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI