half an eye

half an eye (uncountable)

1. A minimal amount of attention.

   to keep half an eye on something

   • 1976, Edward Crankshaw, Joseph Conrad: some aspects of the art of the novel, page 8:

     And if the reader can add that throughout the length of the book, during all his immersion in the author's purpose, he still had half an eye for the means whereby that purpose was achieved, no conceivable harm is done.

   • 2007, Broadview Anthology of British Literature, page 1218:

     As he put it when comparing her to many of her contemporaries, “she liked writing with an intensity which few writers have attained or desired”: Most of them write with half an eye on their royalties, half an eye on their critics, and a third half eye on improving the world, which leaves them with only half an eye for the task on which she concentrated her entire vision.

   • 2017, Alex R. Carver, An Eye For An Eye:

     Burke kept half an eye on the pair as he passed them, but he saw no need to stop and help; the experienced constable appeared to be having no difficulty subduing his man, who seemed to still be dazed from the crash.

2. The slightest ability to recognize or perceive.
   • 1851 June–July (date written), Nathaniel Hawthorne, “The Gorgon’s Head”, in A Wonder-Book for Girls and Boys, Boston, Mass.: Ticknor, Reed, and Fields, published November 1851 (indicated as 1852), →OCLC, page 32:

     Thus (as you will see with half an eye, my wise little auditors) these good old dames had fallen into a strange perplexity.

   • 1851, “An Interview with the Syrio-Lebanon Family”, in Punch, volume 21, page 154:

     The veil would be torn to pieces in less than a week, or would be made so transparent that any one, "with half an eye,"— as the saying is, though we never recollect meeting any one who only had "half an eye" —would be able to see through it; and if any one did take the veil, it would be because she could not get any one to marry her, or because some designing Roman Catholic priest had persuaded her, poor girl, for the sake of her fortune, to go into a convent.

   • 1975, Richard A. Maynard, Propaganda on Film: A Nation at War, page 8:

     If you have half an eye for this sort of thing, you'll know when you first see Esperanza's shiny radio that it will be taken away from her, just as you'll know when you see the photograph of Juarez that it wouldn't be framed except to be smashed.

• keep a weather eye open
• listen with half an ear
• see with half an eye

• “half an eye”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “half an eye”, in Collins English Dictionary.
• “half an eye”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “half an eye ear” in Longman Dictionary of Contemporary English, Longman.