Definition of "oily"

There were no breakers and no waves, for not a breath of wind was stirring. Only a slight oily swell rose and fell like a gentle breathing, and showed that the eternal sea was still moving and living.

1895 May 7, H[erbert] G[eorge] Wells, “The Further Vision”, in The Time Machine: An Invention, New York, N.Y.: Henry Holt and Company, page 195

His clothes were apt to look oily and smell of eating-houses.

1853, Herman Melville, Bartleby, the Scrivener‎

[…] overdressed young men of enigmatic appearance, with oily thick hair, shifty eyes, and hands covered with cheap rings, swaggered about smoking cigarettes and talking in loud, ostentatious voices.

1917, Robert Hichens, Wilderness‎, Chapter

[…] for I want that glib and oyly Art,To ſpeake and purpoſe not, ſince what I well entendIle do’t before I ſpeake, […]

c. 1603–1606 (date written), [William Shakespeare], […] His True Chronicle Historie of the Life and Death of King Lear and His Three Daughters. […] (First Quarto), London: […] Nathaniel Butter, […], published 1608, [Act I, scene i]

Mr. Carker the Manager, sly of manner, sharp of tooth, soft of foot, watchful of eye, oily of tongue, cruel of heart, nice of habit, sat with a dainty stedfastness and patience at his work, as if he were waiting at a mouse’s hole.

1846 October 1 – 1848 April 1, Charles Dickens, “A Trifle of Management by Mr. Carker the Manager”, in Dombey and Son, London: Bradbury and Evans, […], published 1848, page 211

‘He had an inflexible will beneath all that oily kindness which passed for spiritual […] ’

1914, Algernon Blackwood, The Damned‎

Lustered (also called lusters, rainbows, oilies, and pearls).

1998, Joanna Cole, Stephanie Calmenson, Michael Street, Marbles: 101 ways to play

But marbles are not only used to play games: they are also traded. In this market, the value of the different kinds of marbles (oilies, emperors, etc.) is determined by local supply and demand and not by the price of the marbles […]

2001, Paul Webley, The economic psychology of everyday life, page 39