sidle

Etymology

The verb is from side + -le (frequentative suffix), possibly a back-formation from sideling (“in a sidelong direction; askew, obliquely”, adverb), treating that word as the present participle of sidle. The noun is derived from the verb.

verb

1. (transitive, intransitive, also figurative) To (cause something to) move sideways.
   [F]rom the circle of delighted auditors listening to the gentillesses of the pink cockatoo, who was sidling on his stand in the sunshine, a whole party of the Beresfords caught sight of me, and in a minute I was surrounded; … 1836, [Catherine Gore], The Diary of a Désennuyée. … In Two Volumes, volume I, London: Published by Henry Colburn,[…], →OCLC, pages 176–177
   The mare never moved; but after immense weight had been placed on both, the horse began to sidle, and before the last bag could be put on him, he sunk on his knees; it was put on the mare, and she bore it, never moving her posture until she was unloaded. 1842, A. Lawson, “131. The Achievements of the Horse.”, in The Modern Farrier; or, The Art of Preserving the Health and Curing the Diseases of Horses, Dogs, Oxen, Cows, Sheep, and Swine.[…], 25th edition, London: G[eorge] Virtue,[…]; Newcastle: R. Dent, →OCLC, page 257
   You could drive a band of hosses up the steepest kind of hill but nobody that I ever knowed could drive a bunch straight down (that goes with cows, too)—they'd sidle it every time. 2011, Charles M[arion] Russell, “Range Horses”, in Stephen [Vincent] Brennan, editor, The Best Cowboy Stories Ever Told, New York, N.Y.: Skyhorse Publishing, page 478
2. (transitive, intransitive, also figurative) In the intransitive sense often followed by up: to (cause something to) advance in a coy, furtive, or unobtrusive manner.
   A small lad, with a large head and faded yellow hair, sidles up to you, and says something about "Ing'n work," or "Cur'osities," or "Cam'ra 'bscura," or "Guide." You give some sharp, quick answer; the small boy collapses and vanishes. 1853 July, “Niagara”, in Harper's New Monthly Magazine, volume VII, number XXVIII, New York, N.Y.: Harper & Brothers, publishers,[…], →OCLC, page 290, column 2
   A sharper sidleth up to him, "Why bettest thou not?" saith he. For a moment's space the stranger's face Was a wondrous thing to see. This may be a nonce use of the third-person singular simple present indicative form sidleth; other examples of the word, and the second-person singular simple present form sidlest, have not been found. 1877 March, “[Humorous Department.] The Barrel Organ.”, in Belford’s Monthly Magazine. A Magazine of Literature and Art, volume I, Toronto, Ont.: Belford Brothers, publishers,[…], →OCLC, page 589
   One day he sidles up to a group, listens to the conversation for a moment, and actually puts in a remark. "I beg your pardon!" says one of the girls politely who has not heard his modest effort at conversation. For a moment Alexander remains rooted to the ground, he stammers out something unintelligible, the whole group turns and looks at him; this completes his confusion, he turns and sidles back to his seat, his face as hot as can be, and remains lost in a Latin grammer for at least half an hour. 1914 April, Eric H. May, “The Metamorphosis of a ‘Fusser’”, in Paul Sykes, editor, Vox Lycei: Official Organ of the Ottawa Collegiate Institute, volume XXIX, number 1, Ottawa, Ont.: Ottawa Collegiate Institute, →OCLC, page 16
   Marta's gander was a magnificent snow-white bird: the object of terror to foxes, children and dogs. She had reared him as a gosling; and whenever he approached, he would let fly a low contented burble and sidle his neck around her thighs. 1988, Bruce Chatwin, Utz, London: Jonathan Cape; republished London: Vintage Books, 2005, page 50
   Ava tried to sidle away, but she was semi-trapped between the corner of the stage and a French Club sign-up table. 2014, Belle Payton, Too Cool for School (It Takes Two), New York, N.Y.: Simon Spotlight, Simon & Schuster Children’s Publishing Division, page 71
   A man I'd never spoken to before who worked in the IT department sidled behind me as I danced and put his hands on my waist where the cut-outs were. 2021, Megan Nolan, Acts of Desperation, Random House

noun

1. An act of sidling.
   1. A sideways movement.
      [I]n this mythic America, we fly along in the fast lane, placing bets against flashing lights in the rearview mirror, against the dreaded sidle into the gravel and the voice at the window demanding our license. 2015, Meredith Castile, “America”, in Drivers License (Object Lessons), New York, N.Y., London: Bloomsbury Academic, Bloomsbury Publishing, page 1
   2. A furtive advance.