YHWH, Adonay, and Jehovah
I am often asked where the name Jehovah comes from by participants in our Lay School of Ministry. I've used the following brief outline to help explain the origin of this unusual name for God.
YHWH is the Hebrew name of God revealed to Moses. It is comprised of 4 consonants, since Hebrew didn't include the vowels in the written texts. However, with the vowels added, it would look like this:
YaHWeH
Adonay is the name that late Judaism used for God so that they wouldn't have to say YHWH, which was considered far too holy for sinful lips of mortals to utter.
Jehovah is formed by early translators who mistakenly combined the vowels of Adonay with the consonants of YHWH.
Y	a	H	W	e	H		
A	d	O	n	A	y		
Y	a	H	O	V	A	H	
J	e	H	O	V	A	H