adj. slip·per·i·er, slip·per·i·est
1. Causing or tending to cause sliding or slipping: a slippery sidewalk.
2. Tending to slip, as from one's grasp: a slippery bar of soap.
3. Not trustworthy; elusive or tricky: "How extraordinarily slippery a liar the camera is" (James Agee).
[Alteration of obsolete slipper, from Middle English, from Old English slipor; see lei- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendicies
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.