Also called "sub", the poor person, either fresh out of college or old and retired, who fills in for absent teachers. The sub can expect to be ridiculed and tortured by bitch-ass 7th graders who will do anything in their power not to finish an easy worksheet left them by their teacher. The sub is basically a $55/day babysitter.
Bitch-ass kid: Ah hell yeah we got a substitute today! We ain't doin shit! Hey Mister, uhh...Mister!(kid can't read last name on the board because he's an illiterate degenerate) Can I go to da bafroom?
by Zach "Mr." Cress January 25, 2006
5 foot Jen is paying for her college through substitution.
by Lori-Ann January 29, 2008
Whether he gets a phone call from his girlfriend, or splinter in his finger, this social athlete calls full time far too early.
"Where is Ben tonight? It's only 10pm"...... "He's gone home to be a substitute. He'd rather be with the ball and chain".
by TheAthlete November 2, 2014
A person that is only desired or wanted at their significant other's conveinience.
From a quote by "Claire" in the film Elizabethtown

The significant other of the substitute person may not "have enough time" or "be too busy" for a relationship, or they may only be interested for the purpose of sex, money, status, or general need of someone to talk to during times of stress. The substitute person generally won't get the emotional fulfillment from the experience that he/she may crave, and will feel unimportant yet somehow will continue on out of hope.

This can only end in tears for the substitute person.
by Bird Bird Bird April 24, 2010
Any replacement for coffee. Energy drinks are commonly used as a coffee substitute. Tea can be a coffee substitute for some people, as well as caffeine tablets.
Person #1: "Do you still drink coffee?"

Person #2: "Come to think of it, not as much. I am using energy drinks much more often as a coffee substitute."
by yes juanito yes January 24, 2012
Someone who does not know anything about teaching, yet still gets payed while the students don't learn anything that day
We had a substitute teacher today so we didn't do shit
by stanimal51 April 13, 2016
The act of replacing a ligand in a complex ion. This results in a change of colour of the complex ionic solution.
Rasta: What does ligand substitution do?
Me: Ligand substitution results in a different coloured solution!
by TheWizoid November 13, 2016