adj

• (colloquial) Crazy, insane.
  ""You wanted a report, so here's a full report: crazy, nutso, raisins short of a fruitcake, rubber walls, screaming-mad basket-cases.""
• (colloquial) Fraught or out of control.
  "How being taught to not cut corners, even in a nutso emergency room shift, meant I checked all regions in Mary below the waist and didn't just tell her I thought it was probably gas."
• (colloquial) Obsessed; overly enthusiastic.
  "Even the most nutso fisherman would think twice about going out on the lake today."
• (colloquial) Ridiculous; unbelievable or silly.
  "Forget the mechanical, materlial, solid model of communication, bring in the invisible but very real web rings. Internet, hacking and so on; puerile conversations of chat pages, insane obsessions with nutso things."

noun

• (colloquial, countable) A crazy person; a crackpot or lunatic.
  "You know, some computer nerd rapist killer nutso builds a fantasy around her, crashes a party whereshe's supposed to be, she laughs himoff, says she'd rather be fuckin' her girlfriends than a pimply little freak--"
• (colloquial, uncountable) Craziness; insanity.
  "I wrote a letter to the Guild Newsletter apologizing for having disrupted the show, pleading temporary nutso."

adv

• (colloquial) Madly; extremely or obsessively.
  "I'm completely, utterly, nutso in love with that man!"
• (colloquial) In a crazy manner.
  "I'm working at the ink-jet machine running a job...then I hear a weird noise I but I can't really tell what it is over the sound of the machine right.. .then I think I hear a whimper...all of a sudden my step mom bursts out from her office all nutso saying..."where is your father, where is your father""