In the 10 commandments, the word lust (thou shalt not lust) is not even there, BUT the word covet (thou shalt not covet...) is there. Covetousness involves lust. God says, "Thou shalt not covet thy neighbors wife." Which means you should not want or desire to have your neighbors wife. In other words, you should not LUST after your neighbor's wife.
Sice you want to use definitions, let's compare the definition of "lust" you just gave using the dictionary to the definition of "covet" I am about to give using the dictionary.
Main Entry:lust
Function: intransitive verb
Date: 12th century
: to have an intense desire or need : CRAVE; specifically : to have a sexual urge
cov·et ( P ) Pronunciation Key (kvt)
v. cov·et·ed, cov·et·ing, cov·ets
v. tr.
To feel blameworthy desire for (that which is another's). See Synonyms at envy.
To wish for longingly. See Synonyms at desire.
v. intr.
To feel immoderate desire for that which is another's.
They both involve the longing/desire for something lewd or something that should not be yours.