Marked by persevering, painstaking effort. See Synonyms at busy.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "diligent" in a sentence
"Thus, in the example -- "He writes _well_," the adverb shows the manner in which the writing is performed; in the examples -- "He is remarkably diligent" and "He works very faithfully," the adverbs modify the adjective _diligent_ and the other adverb _faithfully_ by expressing the degree of diligence and faithfulness."
"We must remain diligent and protect our freedom to read."
"But a goodly heritage has no worth save in diligent hands."