1. Entirely irrational: Completely unreasonable or lacking any sense of the consequences of actions taken.

2. Affected with dementia: Affected by the loss of intellectual functions that is associated with dementia. This usually only happens to elderly (old) people.
My friend's granpa is demented, he can't remember a thing.
by Jafje March 31, 2007
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Third shift at the Wal-Mart Supercenter in Goshen. See Wal-Mart Mafia
I just went to Wal-mArt and damn those bitches are demented as a motherfucker
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The word means mentally deranged, but so far nobody has mentioned how "demented" can be stretched, ironically, to include clownish, wacky etc. Just the thing for the Urban Dictionary!
"That Debussy Sarabande analysis video is totally demented."
"Nonsense rhyme is so demented."
"The Beatles song "I Am The Walrus" is totally demented."
by anassdickcomesoutfrombehind February 23, 2017
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Someone who has a negative influence;

Causes the world around them to turn to appear deranged.

Unintentionally creates conflict and bad moods to anyone around them.

Attracts negative spiritual energies and entities.
I don't like her, and I don't know why. Maybe she's a Dementer.

Ever since they've gotten here, a lot of weird things have happened. A bunch of Dementers, the lot of them.
by Katja Nightingale January 20, 2012
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Extremely demented, or entirely messed up looking as if it really was demented. Stupid or dumb looking.
Person 1: Did you see Steve's broken arm without the cast?

Person 2: Yeah, it was really dementicated.
by KayleighRae June 10, 2008
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a total and complete loss of logic and reason, dementation is the way forward, dementation
you're gonna be a big star? don't be so bloody demented!
by vijay mahrra February 9, 2004
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demention is the noun version of demented, which gives identity to the various forms of otherwise, cruel and unusual, perverted, insidious, unprosecuted, reprehensible aka demented behavior that typically ensues when one preys upon another ostensibly innocent/underage/powerless/involuntary victim who does not have an equal opportunity to make an informed choice
Once you know the full history of the man, it becomes apparent that many subtle dementions have filtered into the psychoses of Woody Allen's often self autobiographical films.
by tiffanyesq October 17, 2018
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