Literally - The bag of balls thats hangs beneath the penis/cock/dick/nob as part of the male genitalia.

Metaphorically - Someone who you really dislike and want to insult. It usually just comes out as you cannot think of a better insult.
"Jonathan i dislike you"

"Yeah well i think your a complete ... nobsack"
by Josh_Guernsey May 25, 2006
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Multi-purpose term to be used in any number of circumstances. Less harsh than dickhead. A variation on nobhead. Means scrotal sack, or scrotum, but sounds much better and gets quite addictive.
Oi nobsack, do you want a cup of tea?

or

Alright nobsack, what are you up to later?

or

Americans, what a bunch of nobsacks
by Cundyboy January 23, 2004
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a person who is not being very sensible .
for christs sake luke .... grow up and stop being such a NOBSACK.
by tom November 26, 2003
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