do one's best

do one's best (third-person singular simple present does one's best, present participle doing one's best, simple past did one's best, past participle done one's best)

1. To do as best one can.

   Synonyms: try one's best, do one's utmost, give it one's best shot

   • 1971 [1963 November 22], Lyndon Johnson, “The Beginning”, in The Vantage Point‎, Holt, Reinhart & Winston, →ISBN, →LCCN, →OCLC, page 17:

     This is a sad time for all people. We have suffered a loss that cannot be weighed. For me, it is a deep personal tragedy. I know that the world shares the sorrow that Mrs. Kennedy and her family bear. I will do my best. That is all I can do. I ask for your help — and God's.

   • 2022 November 2, Paul Bigland, “New trains, old trains, and splendid scenery”, in RAIL, number 969, page 58:

     Other stops retain no-frills brick-built shelters, although local community rail groups do their best to improve the ambience with planting, posters and artwork.

• do one's worst

• “do one's best”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “do one's best”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “do your best” in Longman Dictionary of Contemporary English, Longman.
• “do try your best” (US) / “do try your best” (UK) in Macmillan English Dictionary.