The Greek word magoi only occurs in Matthew 2 verse 1, 7 and 16 (though also in Acts 13:6,8 with the sense of 'magician / sorcerer')
What does magoi mean?
It is the plural of magos, which my Abbot-Smith Greek Lexicon defines as "A Magian, one of a sacred caste, originally Median, who seem to have conformed to the Persian religion, while retaining some of their old beliefs."
How do the different versions of the Bible translate it into English?
Authorised Version: wise men
(also Revised Version, Revised Standard Version, New Revised Standard Version, Jerusalem Bible, International Children's Bible)
New English Bible: astrologers
(also Revised English Bible, Living Bible)
New International Version: Magi
Good News Bible: some men who studied the stars (but simply visitors in verses 7 & 16)
J.B. Phillips: a party of astrologers (but wise men in verses 7 & 16)
The Message: a band of scholars
So why do they appear as kings in nativity plays?
Maybe because they were seen as the fulfilment of Old Testament prophecies:
Psalm 72:10 - "May the kings of Tarshish and the isles render him tribute, may the kings of Sheba and Seba bring gifts."
Isaiah 49:7 - "Kings shall see and arise; princes, and they shall prostrate themselves."
Isaiah 60:3 - "Nations shall come to your light, and kings to the brightness of your dawn."
They first appear as kings in Tertullion (c.160-c.225 A.D.)
The number three (because of the three gifts) appears in Origen (c.185-254 A.D.)
Other early Christian traditions have the number as twelve.
For Matthew, they represent the Gentile nations who recognise and pay respect to the Messiah.
That's the boring academic bit over, now on with the doggerel...
(To be properly appreciated the following needs to be read aloud. The underlined syllables should help you put the stress in the right place.)