This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
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adj. Of a person, taking their work seriously and doing it well and rapidly.

adj. habitually working diligently and for long hours.

adj. characterized by hard work and perseverance

"Everybody knows that Obama was exceptionally bright and hardworking from a young age."

diligent   

industrious    tireless    untiring   

industrious    thrifty    enterprising    kind-hearted    trustworthy    diligent    law-abiding    self-respecting    virtuous    sober