To be lazy or to fail to put in effort.

आलसी होना

English Usage: She was slacking off during the group project.

Hindi Usage: वह समूह परियोजना के दौरान आलसी हो रही थी।

The act of being lazy or not doing one's work properly.

ढिलाई करना

English Usage: His slacking at work led to missed deadlines.

Hindi Usage: उसके काम में ढिलाई करने के कारण समय सीमा चूकी।