kook

1. (slang, chiefly US) An eccentric, strange or crazy person.Examples: "The kook we will always have with us, to paraphrase Jesus, but the kooks of yore had to work to maintain their kookery and locate fellow kooks. They had to pick up their kook phone, subscribe to the kook newsletter, drive to the kook convention. Nowadays, all the kook has to do is log in to Facebook, where his feed will be enlivened by the chatter of fellow — and likely more extreme — kooks, toward which Facebook’s algorithms helpfully steer him."; "The administration’s deep cuts to scientific and medical research have been compounded by Trump’s decision to hand control of public health to Robert F. Kennedy Jr., a bona fide kook,[…]."Synonyms: nutjob, odd duck, weirdo, basket case, basket weaver, crack, crackpot, crazyUSslang

2. (surfing, kiteboarding, wakeboarding) A boardsport participant who lacks style or skill; a newbie who acts as if they are better at the sport than they are.