Neil Turner

lackadaisical (adjective) – done in a lazy and/or uninterested way

lackadaisicalness (noun) – a lazy and/or uninterested way of doing things
lackadaisically (adverb) – in a lazy and/or uninterested way

Examples:

“If you don’t mend your lackadaisical ways, young lady,” said the teacher, “you never will go far.”

The table was set in lackadaisical manner with different plates and mismatched cups and glasses.

The lack of organization of its webpages showed a total lackadaisicalness that ignored rule number one of websites, which is that they should be user-friendly.

“I’ll do it tomorrow,” she said lackadaisically.

They had a day off and stayed in bed all day, reading on their tablets and fetching food from the fridge lackadaisically.