Top Definition
the ancestor of prokaryotic cells. it was basically a bunch of organic molecules surrounded by a membrane. they exhibit some properties associated with living organisms, such as reproduction, metabolism, and what may be a precursor to homeostasis. they may have formed spontaneously in the conditions found on earth around 3.8 billion years ago or perhaps even farther back.
*in Biology class*

"OH MY GOD. Dude. I just found an organism that is way too small to be considered a bacteria, but it seems to reproduce and metabolize itself."
"Yeah, you have a nanobacterium on your hands."
"WTH is a nanobacterium?"
"Oh, nothing, just an organism that some scientists don't consider an organism. It's totally real, though, because it's a modern protobiont."
"WTH is a protobiont?"
"HOW are you in biology?? Just look it up on Urban Dictionary."
by alee-marie September 09, 2012

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt