conscientious

From Middle French conscientieux, from Medieval Latin cōnscientiōsus. Its English equivalent could possibly be analyzed as conscient +‎ -ous. See more at conscience.

• (UK) IPA^(key): /ˌkɒnʃiˈɛnʃəs/
• (US) IPA^(key): /ˌkɑnʃiˈɛnʃəs/

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conscientious (comparative more conscientious, superlative most conscientious)

1. Thorough, careful, or vigilant in one’s task performance; painstaking.

   He was a thoughtful and conscientious worker.

2. Influenced by conscience; principled; governed by a strict regard to the dictates of conscience, or by the known or supposed rules of right and wrong (said of a person).

   Synonym: faithful

   The advice of wise and conscientious people.

• “conscientious”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “conscientious”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.
• “vigilance” in Roget's Thesaurus, T. Y. Crowell Co., 1911.