slithery

From Middle English slidery; equivalent to and remodelled as slither +‎ -y.

slithery (comparative slitherier, superlative slitheriest)

1. That slithers; that moves like a snake.
   • 1904, Arthur Conan Doyle, “The Adventure of Charles Augustus Milverton” in The Return of Sherlock Holmes,

     Do you feel a creeping, shrinking sensation, Watson, when you stand before the serpents in the Zoo, and see the slithery, gliding, venomous creatures, with their deadly eyes and wicked, flattened faces? Well, that’s how Milverton impresses me.

   • 1941, Emily Carr, Klee Wyck, Chapter 18,

     […] we set out for the cannery. There, men with spiked poles would swarm into the scow, hook each fish under the gills. The creatures would hurtle through the air like silver streaks, landing into the cannery chutes with slithery thumps, and pass on to the ripping knives

   • 2001, Fernando Pessoa, The Book of Disquiet, translated by Richard Zenith, Penguin, “Triangular Dream,” p. 243,

     They are doubts from the abyss that drag their cold and slithery bodies across the soul.

2. Sneaky, underhanded; insincere.
   • 1977, John Show, “Stilled Life,” Time, 29 August, 1977,

     The suspects include mischievous caricatures from the New York art world-a guileful art dealer, a slithery lawyer, a glittering female collector of celebrities, a vacant former model who is Maitland's widow, and so on.

3. Slippery, causing one to slither.
   • 1922, Eric Rücker Eddison, The Worm Ouroboros, Chapter 26,

     But a little while only would he suffer us to halt; then right we turned, up along the ridge, where the way was yet worse than in the dale had been, with rocks and pits hidden in the heather, and slithery slabs of granite.

   • 1926, Edgar Wallace, The Black Abbot, Chapter 29,

     She led the way, stepping gingerly on the slithery moss.

   • 1957, “How to Lose Fear,” Time, 19 August, 1957,

     Attempted but never conquered was a possible fifth way, the Grand Pilastre, a 5,000-ft. perpendicular wall of gripless, smooth rock and slithery green ice that looms over empty space toward the summit.