wealthiness comes from wealthy (from wealth, from Middle English welthe, formed on Old English wela 'well-being, prosperity') plus -ness. Morphologically, the word is transparent: -ness is attached to the older base named in the history, so the modern form packages an inherited or borrowed stem inside a later English derivative. In modern use, the noun sense is "the state of being rich or having abundant possessions", which keeps the etymology connected to the word's present dictionary value rather than treating it as a merely historical label. The wider word family includes related English forms such as wealthy, wealth, weal, showing how the same base continues to support neighboring English vocabulary. The principal historical forms in the chain include Old English wela, Old English wel, which anchor the explanation in named linguistic material.