Female version of a Nincumpoop. Someone who is being silly, stupid or without reasonable thoughts.
Sarah you big ninnie, you just put your car keys in the ice box

Or

If Beth is a class clown you might say
Beth is a ninnie
by ddlD2 March 17, 2014
Get a ninnie mug for your mama Julia.
Shortened version of nincompoop, a silly, idiotic person. can be used affectionately.
you went into the girls bathroom by mistake? you ninny!
by Shwaggy November 18, 2003
Get a ninny mug for your bunkmate Riley.
Quite possibly the coolest insult ever. Short for nincompoop, it was used often in Victorian Europe and early North America. Insult of choice for monocole-wearing gentry, and anyone with a bit of class.
My, what a ninny! *monocle*

Ninnies + potatoes = sign of good will?
by Rivviko September 10, 2007
Get a ninny mug for your mate Vivek.
1. An idiot
2. Short word for nincompoop
3. Someone who is afraid of everything and has no courage; see pansy
by Turd Ferguson January 29, 2004
Get a Ninny mug for your sister Nathalie.
THE SHIP NAME FOR VINNIE AND NAILEA BC THEY ARE PERFECT FOR EACHOTHER
by January 18, 2021
Get a NINNIE mug for your bunkmate James.
short for nincompoop, a silly, stupid person. often used affectionately.
you went into the girls bathroom by mistake? you ninny!
by Shwaggy November 18, 2003
Get the ninny neck gaiter and mug.