Como dizer "má vontade" em inglês

Sure, in Portuguese we can say: má intenção

Example:

In the States, where I am considered a world traveler by my family, on more than one occasion, my uncle who served in Korean War and was a POW said "Jap" without thinking and without any ill will around my Japanese wife.

Yeah. I think "ill will" is more used to mean enmity, hostility and hate.

Eg: He suffered the same pain as me, yet bore no ill will!

I think I prefer "grudgingly" in the example above, in the sense of unwillingly.

@Tim

Thanks a lot for this new word to me.
Definition-->begrudge=to feel annoyed or unhappy that you have to pay something, give someone something etc
example: I begrudge spending so much money on train fares( Eu gastei, de má vontade, muito dinheiro com a tarifa de trem)
source: longman

How about "begrudgingly"
He swept the back yard begrudgingly because he wanted toplay football with his mates.
Tim

You may say "with a bad grace" for adverbial circumstances; "unwillingness" would be used as noun meaning lack, want of will or a disposition contrary to do anything. I´d be very pleased if any friend might shed brighter commentaries about.