upon the instant

upon the instant (not comparable)

1. (idiomatic, dated) Immediately, right away.

   Synonyms: see Thesaurus:immediately

   • 1843 December 19, Charles Dickens, “Stave Two. The First of the Three Spirits.”, in A Christmas Carol. In Prose. Being a Ghost Story of Christmas, London: Chapman & Hall, […], →OCLC, page 42:

     Light flashed up in the room upon the instant, and the curtains of his bed were drawn.

   • 1886 January 5, Robert Louis Stevenson, “Doctor Lanyon’s Narrative”, in Strange Case of Dr Jekyll and Mr Hyde, London: Longmans, Green, and Co., →OCLC, page 103:

     Or, if you shall so prefer to choose, a new province of knowledge and new avenues to fame and power shall be laid open to you, here, in this room, upon the instant; and your sight shall be blasted by a prodigy to stagger the unbelief of Satan.

   • 1908, Howard Pyle, “The Terrific Encounter With the One-eyed Little Gentleman in Black”, in The Ruby of Kishmoor, New York, N.Y., London: Harper & Brothers Publishers, page 34:

     "That ball!" he cried, in a hoarse and raucous voice. "That ivory ball! Give it to me upon the instant!"

• “instant, n.”, in OED Online ⁠, Oxford: Oxford University Press, launched 2000.