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4.
the Only Child is a clever species which mimics the Regular Human. Indistinguishable by simply looking at them, you must get to know an Only Child to know that they are, in fact, an Only Child. As a species they tend to appreciate being alone more so than the Regular Human, and more often like quiet thinking time and don't mind hanging out by themselves. At a young age, all Only Children tend to go through an elongated "brattiness" phase, which tends to be more extreme than that of a Regular Human child. Depending on the parents, the Only Child may eventually grow out of this phase, and surrounded by Regular Human friends, can blend in perfectly. The Only Child has been observed to experience loneliness quite often, and usually feels that this loneliness can be filled best by a relationship, and extreme cases the longing for a relationship can be more important than maintaining the type of friendship observed in the species "Regular Human". However, it is indeed common for an Only Child to fall harder and faster when it comes to relationships, and tend to experience emotions more intensely. If an Only Child has trouble finding an acceptable relationship, they may become uncomfortably hormonal. For example, it is possible that a female only child could even have as many hormones as a 17-year-old male. Which is a fuckton load. Only Children also love Pokemon, especially Wooper.
1. Bro 1: If I ever have kids, I'm def gonna have more than one. I don't want to have to raise a bratty, over-hormonal only child.

2. She must have gotten through her annoying only child phase, because we've been friends for years and I just assumed she had siblings.

3. Duder 1: Man, that bitch is such an only child. When I asked her to fuck she got all emotional and now she's telling people we're dating. WTAF.
by ilovethesilverfox January 01, 2012
 
1.
a person who has no brothers or sisters.

has its pro's and con's, you usually can mamange to get whatever you want, you don't have to deal with any annoying little brats or other siblings who irk you, but most of the time, it's lonely.
jenny has no brothers or sisters, she's an only child.
by i wanna be a kennedy October 21, 2005
 
2.
someone who has never had siblings
someone the oldest child previously was
Miranda Cosgrove of iCarly is an only child in real life.

SakuraSaku (that's me!!!)is an only child as well.
by SakuraSaku April 30, 2009
 
3.
Someone who has no siblings. Some upsides are getting what you want, having some friends that are only children, no being irked, and having higher goals. Downsides are lashing anger on kids who have siblings, and can end up being a jerk. Sometimes it leads to having an inflated ego.
Friend 1: How's your sister?
Friend 2: Pretty good. She's playing soccer.
Only child: I'm frickin' tired about my brother that, and my sister this! Screw all of you! *walks away*
Friend 1: God, what a jerk.
Friend 2: I know.
by yahmoo23 April 15, 2010