In the Torah
In the Book of Numbers the Levites were charged with ministering to the Kohanim (priests) and keeping watch over the Tabernacle:
And thy brethren also, the tribe of Levi, the tribe...
A Levite is from the tribe of Levi (descendants of Levi). The Levim (pl) make up the priestly class in Judaism and the Cohenim (high priests) come from this tribe. All Levi males are priests with the...