Craziness is wild unreasonable behaviour. The craziness of it, sheer craziness, all this craziness.
It is informal and usually about a situation rather than a person, which is what keeps it away from being a comment on mental health. Applied to people it is best kept for affection or for exaggeration, since the alternative is unkind.
1nouncrazinessWild unreasonable behaviour.
“With three kids, two dogs and a new baby, the craziness at home never stops.”
craziness is a behaviour.
From crazy + -ness.
Etymology from Wiktionary, CC BY-SA