"kookness" means: Kookness is the noun form of 'kook' — capturing the quality or degree of someone's eccentricity, weirdness, or unhinged charm. Whether someo.... This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.