Stoutness is a synonym of lustiness.
As nouns the difference between stoutness and lustiness
is that stoutness is (usually|uncountable) a state or quality of being stout while lustiness is the property of having or experiencing lust, of being lusty.
stoutness
English
Noun
(es)
(usually, uncountable) A state or quality of being stout.
(countable, rare) The result or product of being stout.
lustiness
English
Noun
(lustinesses)
The property of having or experiencing lust, of being lusty.