se'nnight

plural se'nnights

1. alternativeAlternative form of sennight, a week.

   We leave Bath, as she has perhaps told you, on Saturday se'nnight.

   1803 (date written), [Jane Austen], chapter II, in Northanger Abbey; published in Northanger Abbey: And Persuasion. […], volume I, London: John Murray, […], 20 December 1817 (indicated as 1818), →OCLC, pages 26–27

   3 more examples

   It will be in my power to assure him that her ladyship was quite well yesterday se'nnight.

   1813 January 27, [Jane Austen], chapter XVIII, in Pride and Prejudice: […], volume I, London: […] [George Sidney] for T[homas] Egerton, […], →OCLC, page 224

   I was snowed up at a friend's house once for a week. Nothing could be pleasanter. I went for only one night, and could not get away till that very day se'nnight.

   1815 December (indicated as 1816), [Jane Austen], chapter XIII, in Emma: […], volume I, London: […] [Charles Roworth and James Moyes] for John Murray, →OCLC, page 244

   Old woman, what was it the village Elders said a se'nnight since? Eh? Stir your memory.

   1948 (1st collected edition 1953), Isaac Asimov, “Two Men and a Peasant”, in Second Foundation, New York, N.Y.: Del Rey, published 2020, →ISBN, part I (Search by the Mule), page 41