And she conceived again, and bare a son; and said, Now this time will my husband be joined unto me, because I have born him three sons: therefore was his name called Levi. Genesis 29:34 (KJV)
The Hebrew verb לוה lavah (#3867) means "to join" such as we can see in the verse above. This is the root of the name לוי leviy (#3878), meaning "joined," and is also found in the verse above. Both of these words are also found in the following verse.
And thy brethren also of the tribe of Levi, the tribe of thy father, bring thou with thee, that they may be joined unto thee, and minister unto thee: but thou and thy sons with thee shall minister before the tabernacle of witness. Numbers 18:2 (KJV)