Joash = "given by the Lord"
derivation: a form of (03060)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=03101&version=kjv

(03060)
Jehoash = "given by the Lord"
derivation: from (03068) and (perhaps) (0784)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=3060&version=kjv

(03068)
Jehovah = "the existing One"
derivation: from (01961)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=3068&version=kjv

(01961)
1] to be, become, come to pass, exist, happen, fall out
   1.a] (Qal)
       1.a.1] to happen, fall out, occur, take place, come about, come to pass
       1.a.2] to come about, come to pass
           1.a.2.a] to come into being, become
       1.a.3] to arise, appear, come 1a
       1.a.4] to become
           1.a.4.a] to become
           1.a.4.b] to become like
           1.a.4.c] to be instituted, be established
           1.a.4.d] to be
       1.a.5] to exist, be in existence
       1.a.6] to abide, remain, continue (with word of place or time)
       1.a.7] to stand, lie, be in, be at, be situated (with word of locality)
       1.a.8] to accompany, be with
   1.b] (Niphal)
       1.b.1] to occur, come to pass, be done, be brought about
       1.b.2] to be done, be finished, be gone
derivation:  a primitive root [compare (01933)]
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=1961&version=kjv

(01933)]
1] Qal)
   1.a] to fall
   1.b] to be, become, exist, happen
derivation: a primitive root [compare (0183)]
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=1933&version=kjv

(0183)
1] desire, incline, covet, wait longingly, wish, sigh, want, be greedy, prefer
   1.a] (Piel) to desire, crave (food and drink)
   1.b] (Hithpael) to desire, long for, lust after (of bodily appetites)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=183&version=kjv

(0784)
1] fire
   1.a] fire, flames
   1.b] supernatural fire (accompanying theophany)
   1.c] fire (for cooking, roasting, parching)
   1.d] altar-fire
   1.e] God's anger (figuratively.)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=784&version=kjv

A link to each occurrence of this word in the homepage:
1] Joash