1) One who is no longer able to use his/her mind.

2) Not effectual; void.
1) The disease turned Marty into an invalid before killing him; we miss him dearly.

2) The ticket is invalid west of the Mississippi, though, so choose carefully.
by Diggity Monkeez April 8, 2005
Inconsistent with some web programmer's arbitrary and frequently incorrect notion of how the world should be.
A: Why does that web site say that your university is in England when it is really in Sweden?

B: Because when I enter the correct address, the web site rejects the postal code as 'invalid'.
by P J Wonko March 14, 2013
A person incapable of doing things for him or herself, also known as a turd
Mom: Let me drive you to work!
Girl: No thanks, Mom. I'm not an invalid.
Mom: Please, let me help you with something!
by Katy Schmieds April 22, 2015
Someone with a lack of possibility. Otherwise known as a moron.

Refer to examples such as jeremy's face or shahpur's arguments.

Person1: Your face is invalid.
Jeremy: What?
Person1: Point proven

Shahpur: I am epic
Person1: o really?
Shahpur: I walked in uber cold weather without gloves or scarf for 30 mins
Person1: I walked in uber hot weather without gloves or scarf

Person1 = WIN
Shahpur = INVALID
by s3xy_c4t December 8, 2008
N. An individual who is unable to communicate.
My boss is an invalid who speaks over others, or at others, but not with others.
by Her 2 January 27, 2018
Person1:“God there so invalid
Person 2:“Probably Perceillas”
by SugarWater09 May 22, 2019
An invalidator is any person who is, for whatever reason, prone to being jealous and insecure. In order to think well of themselves, they will say and do whatever they can to harm the target of their jealousies and insecurities, and to discredit them in any way they can. This gives them a false sense of self-worth and superiority. They are all about bringing out the worst in others, and they will use any unscrupulous, malicious, or manipulative tactic in order to achieve this end.

The best ways to confront an invalidator may include simply ignoring them, proving their accusations to be false, or to respond to their negativity with kindness or humor.
Invalidator: "Bob is just useless jagoff. He isn't worth keeping around. We need to get rid of him."
Bob: "I believe you are mistaken, sir."
Invalditor: "Who cares? Go away. No one likes you here. You're a scumbag!"
Bob: "Is there a problem?"
Invalidator: "You're an asshole. We all know it. Get out of here. You're not worth it."
Bob: "I think your attitude is completely rude, sir."
Invalidator: "I'm not being rude. I'm just telling it to you like it is. No one else has the heart to tell you this, but you're a useless asshole. Nothing you say matters. You're not likeable. You're not a person. You are nobody. Know this. Believe it harder than anything else."
Bob: "Whatever you say."
by Adam Bestler October 15, 2011