Freakishness is the noun: the quality of being very unusual and strange, and sometimes frightening. You might talk about the freakishness of a storm, of the weather this year, or of a coincidence that feels too neat. It is not an everyday spoken word; people are more likely to say something is freakish or freaky, and leave the -ness form for writing or a careful description. It names the strangeness itself, not the person. Be gentle with it around people — freak has a history of being used as an insult for someone who looks or acts different, so calling a person’s body or manner “freakishness” can hurt even when you only meant “unusual”.