I. mis ‧ sion ‧ a ‧ ry 1 /ˈmɪʃən ə ri $ -neri/ BrE AmE noun ( plural missionaries ) [countable]
someone who has been sent to a foreign country to teach people about Christianity and persuade them to become Christians
II. missionary 2 BrE AmE adjective [only before noun]
1 . relating to the work of missionaries:
missionary work
a missionary hospital
2 . missionary zeal if you do something with missionary zeal, you do it with great eagerness, because you believe strongly that it is a good thing to do:
a young English teacher who taught poetry with missionary zeal