Definition of half-ass in US English:

half-ass

(British half-arse)

verb

[with object]informal
  • Do (something) with little effort or care.

    ‘they half-assed the redesign’
    ‘you could just half-ass it’
    • ‘Keep in mind that they are notorious for half-arsing things and doing everything as inefficiently and ineffectively as possible.’
    • ‘When you hit the gym hard, you don't want to half ass it!’
    • ‘Based on his previous behaviour, I'd say he has it in him to dig his heels in and half-arse it until the club becomes fed up and wants him gone.’
    • ‘He's too passionate and willful to half-ass anything in the footballing world.’
    • ‘We have a tendency to half-ass everything and we wonder why nothing works 100 %.’
    • ‘If you are going to half ass the indycar articles, just don't write them.’
    • ‘No matter what they were asked, The Beatles never half-assed it.’
    • ‘Take a tip from famed poet Charles Bukowski and stop half-arsing your way through those new years resolutions.’
    • ‘I would hate to see them half-ass something like this.’
    • ‘Don't half ass it, guys - expect to be repaid in playoff revenue.’

adjective

informal
  • Done with little effort or care.

    ‘he did a half-ass job’
    • ‘The half-ass apology immediately afterward was better than the joke.’
    • ‘To me, that's a half-ass job that provides little value, and gives consultants a bad name.’
    • ‘There is no way we should come up with half-arse theories about what is going on.’
    • ‘When people do that half-arse thing of saying "I don't want to talk about it", it really annoys me.’
    • ‘This firmware is an example of a half-ass attempt at rectifying some of their errors.’
    • ‘Giving me that half-ass sales pitch won't work.’
    • ‘We have watched him put in a half-ass effort in Nashville for years.’
    • ‘He throws an interception and makes a half-arse attempt at a tackle.’
    • ‘That's so half-ass, it's almost funny.’
    • ‘Each workout is like a brick in a building, and every time you go in there and do a half-ass workout, you're not laying a brick down.’