look up any word, like fleek:
 
1.
the person one dates, makes out with, or sleeps with while waiting or actively searching for the love of one's life - who is quite often found during or immediately after relationship with said placeholder.
Though also viable, cute, and longing for a longterm relationship, there is often some unknown 'thing' in the placeholder's manner, ambition, world view, or timing that often prevents the placeholder from being "the one."
"I just found out Chris married the woman he started dating when he was still sleeping with me. He told me he didn't want a serious relationship. I feel like such a placeholder."
by 50_dates May 03, 2012
 
2.
When someone is dating someone else just for them to be there, simply to be able to say "yeah I'm actually taken" even though they hate each other.
"I swear to God, Nick is just using Jen as a Place-Holder!"

"I'm bored....Lets go find us some place holders" -- guys

Friend 1 - "God i fucking hate Michelle!"
Friend 2 - "Aren't u dating her?"
Friend 1 - "Yeah"
Friend 2 - "Well here she comes"
Friend 1 - "Hey baby!"
by Krzysztof January 30, 2008
 
3.
The guy/girl that is dated or messed around with until the user can get the guy/girl that ditched them to come back.

Often the user was just a place-holder for said ex and didn't know it/can't get over him/her.
girl:Oh yeah I can't wait to hang out with you tomorrow <33!! love you baby
guy:*awesome this is love ^.^*

The following Evening:

girl:Yeah...I'm back with <insert douchebag that just ruined your fucking life> and I wasn't really in love with you.
guy:*Holy fucking shit I'm going to kill myself as soon as I finish thinking this.*

Perfect example of a Place-Holder...often suicide IS the result of being a Place-holder.
Other results are binge-drinking and death threats.
by Heyfml April 19, 2011
 
4.
A word used to avoid a question you don't want to answer. A universal word. They're not very specificand leave you in doubt.
"I have to do SOMETHING afterschool."
"Theres this thing I have to do."
"Theres a lot of stuff in my head."
Those are placeholders..
by yepyeahyesss February 26, 2009
 
5.
1.When you dating someone just to get over someone or just dating around until you're ready to get back on horse.
You Know Dave is Sally's place-holder, Until she's ready to walk down the aisle. Poor Dave
by ryukage99 July 02, 2011
 
6.
A non-smoker who is left to guard a table and/or chairs in a busy environment while the smokers go outside for a cigarette.
Tom : "It's busy, we could lose the table."

Dick : "Don't worry, Harry's our placeholder."

Harry : "Thanks a bunch."
by flynnbarr March 20, 2010