Harry … doodled idly on his parchment ignoring Hermione's frequent glares and nudges … J. K. Rowling
b
: in a lazy or inactive manner or state
sat with her hands resting idly in her lap
spent the day lying idly on the couch
Barber left London the next day, and for six months sat idly in Addis Ababa waiting for something to happen. Waverly Root
c
: without taking any action
"The time has come to speak," she said. "I cannot stand idly by[=do nothing] and see a young man going to perdition!" P. G. Wodehouse
… a party who has been wronged by a breach of contract may not unreasonably sit idly by and allow damages to accumulate. John D. Calamari and Joseph M. Perillo
Word History
First Known Use
before the 12th century, in the meaning defined above
Time Traveler
The first known use of idly was before the 12th century