/ ˈmɪʃənri; NAmE -neri/ noun
( pl. -ies ) a person who is sent to a foreign country to teach people about Christianity :
Baptist missionaries
missionary work
( figurative )
She spoke about her new project with missionary zeal (= with great enthusiasm) .
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WORD ORIGIN
mid 17th cent.: from modern Latin missionarius , from Latin missio , from mittere send.