Synonyms for Diligently:

adv.

attentively (adverb)
heedfully, attentively, responsibly, watchfully, alertly, scrutinizingly, raptly, concernedly, vigilantly, observantly, intently, mindfully, cautiously.
busily (adverb)
vigilantly, indefatigably, carefully, persistently, fervently.
fastidiously (adverb)
flawlessly, squeamishly, priggishly, fastidiously, scrupulously, conscientiously, properly, meticulously, perspicaciously, delicately, precisely, fussily, accurately, carefully, primly, correctly, critically, daintily, severely, methodically, Hypercritically, particularly, exactingly, rigorously.
hard (adverb)
intently, doggedly, thoroughly, steadily.
resolutely (adverb)
indomitably, dauntlessly, relentlessly, heartily, fearlessly, determinedly, boldly, stubbornly, doggedly, courageously, steadily, devotedly, truly, toughly, indefatigably, tirelessly, deliberately, decisively, pluckily, loyally, persistently, decidedly, valiantly, staunchly, resolutely, tenaciously, faithfully.
tenaciously (adverb)
stonily, steadfastly, unflaggingly, enduringly, bravely, stiffly, fervently, strongly, undauntedly, obstinately.
vigilantly (adverb)
thoughtfully, strictly, providently, thoroughly, prudently.

adv

attentively (adverb)
intently, responsibly, heedfully, scrutinizingly, raptly, watchfully, concernedly, mindfully, attentively, alertly, cautiously, observantly, vigilantly, carefully.
fastidiously (adverb)
flawlessly, squeamishly, priggishly, fastidiously, scrupulously, conscientiously, properly, meticulously, perspicaciously, delicately, precisely, fussily, accurately, carefully, primly, correctly, critically, daintily, severely, methodically, Hypercritically, particularly, exactingly, rigorously.
hard (adverb)
doggedly.
resolutely (adverb)
faithfully, intently, staunchly, deliberately, loyally, fearlessly, boldly, heartily, determinedly, persistently, relentlessly, resolutely, tenaciously, tirelessly, pluckily, indefatigably, dauntlessly, indomitably, decidedly, steadily, valiantly, toughly, stubbornly, doggedly, decisively, truly, courageously, devotedly.
tenaciously (adverb)
fervently, truly, resolutely, indefatigably, heartily, doggedly, tirelessly, enduringly, tenaciously, undauntedly, devotedly, courageously, stonily, faithfully, pluckily, steadfastly, strongly, indomitably, dauntlessly, persistently, stubbornly, bravely, staunchly, boldly, toughly, decisively, obstinately, stiffly, determinedly, unflaggingly.
vigilantly (adverb)
fussily, cautiously, particularly, fastidiously, precisely, watchfully, providently, carefully, mindfully, thoroughly, attentively, conscientiously, strictly, prudently, scrupulously, alertly, heedfully, vigilantly, thoughtfully, meticulously, exactingly.

Other synonyms:

adv
indefatigably, persistently, vigilantly.
n.
carefully, cautiously, devotedly, doggedly, faithfully, fervently, heedfully, indefatigably, loyally, mindfully, persistently, relentlessly, resolutely, tenaciously, thoroughly, thoughtfully, tirelessly, unflaggingly.

Usage examples for diligently

  1. Here he read the Old Testament diligently but he found in it only the teaching he had formerly received. – Some Jewish Witnesses For Christ by Rev. A. Bernstein, B.D.
  2. He said no more, but taking his tools and two pieces of wood, he set to work diligently – The Adventures of Pinocchio by C. Collodi--Pseudonym of Carlo Lorenzini
  3. The king was pondering the whole subject most diligently – Project Gutenberg History of The Netherlands, 1555-1623, Complete by John Lothrop Motley