Abstract nouns may be formed from adjectives by adding the suffix -ness: happy/ happiness, sad/sadness, kind/kindness, cheerful/cheerfulness.
However, a large group of adjectives have distinct nouns that do not require a formation with -ness or any other suffix. A common stylistic fault is to add the -ness ending to adjectives that already have corresponding noun forms. For example, the adjective humble has the corresponding noun humility, but many English speakers don’t seem to be aware of it and write “humbleness” instead.
Here are a few examples from the web that illustrate the unnecessary use of –ness to form abstract nouns:
I admire his courageousness on choosing a role that was really hard to portray…
She believed that pride and lack of humbleness was against the teaching of the Bible.
Politicians Need More Humbleness
A real story made me to realize that i have hidden my braveness so many days inside me.
This emphasis on responsibleness is reflected in the categorical imperative of logotherapy
Developing Moral Responsibleness Through Professional Education (title of book written by a professor of educational psychology)
“Hey guys” she said coyly, using the maximum of her sexiness and intelligentness.
I wondered at my luckiness
Here are several additional adjective/abstract noun pairs that seem to have escaped the notice of many journalists and bloggers: