1. (派往国外的)传教士
    A missionary is a Christian who has been sent to a foreign country to teach people about Christianity.

2. 传教的;布道的
    Missionary is used to describe the activities of missionaries.

    e.g. You should be in missionary work.
           你应该从事传教工作。

3. (热情)传教士般的
    If you refer to someone's enthusiasm for an activity or belief as missionary zeal, you are emphasizing that they are very enthusiastic about it.

    e.g. She had a kind of missionary zeal about bringing culture to the masses.
           她对于向大众传播文化有着满腔的热忱。