Possibly of East London origin, typically, meaning a weak polite form of 'no' but often 'Nah' is a negative when the speaker is certain that the listener is incorrect and both know that fact for certain but the listener is doublethinking themselves into belief.
"My boyfriend wants to marry me but he isn't ready to get married.. we both have houses to sell before we move on.. my boyfriend needs to sort his shed out before we can get married and support each other but for now he's put me on the game to help out.. I do have my 'hero' and he wants to marry me"
"Nah"
"Nah"
by VapourTrail July 19, 2021
Get the Nahmug. by Sad time waster November 15, 2019
Get the Nahmug. by dannyboss August 27, 2021
Get the Nah he tweakinmug. 
