The present participle of the verb “to noth” which means to do nothing.
It is to be used in the same way a basically any other word ending in -ing.
In the past tense, one could say they had nothed or in the future tense, they could say they will noth. It is a regular verb and follows normal grammar rules.
Guy 1: what were you doing last week?
Guy 2: sleeping mostly. You?
Guy 1: nothing
Something that is impossible. Like how everyone says 'Nothing' is impossible ". Therefore nothing is something that is impossible.
Person A: Watcha doin?
Person B: Nothing.
Person A: IMPOSSIBLE!