Top Definition
The sensation of being half conscious or only partially awake usually occurring immediately after waking up. It is also accompanied by a desire to continue sleeping.
Jim awoke early one morning for work after a rather weak-ass sleep. The force of his sleep inertia was strong that morning. So strong in fact that Jim couldn't help himself but fall back to sleep, consequently missing his shift.
by Woody89 July 27, 2012

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A result of not having social commitments that you care about, leading to a lack of fomo which makes you revert to a human's natural state of sleeping for hours on end.
"I slept for 12 hours last night and I'm still tired?"
"Yup probably cause of sleep inertia."
by Calkimchi September 06, 2015

The Urban Dictionary Mug

Lotsa space for your liquids.

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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