slip 1 
(slĭp)
(slĭp)v. slipped, slip·ping, slips
v.intr.
1.
a. To move smoothly, easily, and quietly: slipped into bed.
b. To move stealthily; steal: slipped out the back door.
2.
a. To escape, as from a grasp, fastening, or restraint: slipped out of the wrestler's hold.
b. To put on or remove a piece of clothing smoothly or quietly: slipped into a nightgown; slipped out of the shirt.
3.
a. To slide involuntarily and lose one's balance or foothold. See Synonyms at slide.
b. To move accidentally out of place or fail to gain traction: The gear slipped.
4.
a. To pass gradually, easily, or imperceptibly into a different state: He slipped into a coma.
b. To decline from a former or standard level; fall off: The senator's popularity has slipped.
c. To elapse, especially quickly or without notice: The days slipped by.
5. To fall into fault or error. Often used with up.
v.tr.
1.
a. To place or insert smoothly and quietly: She slipped the letter into her pocket.
b. To insert (a remark, for example) unobtrusively: managed to slip his criticisms in before the end of the meeting.
2. To put on or remove (clothing) easily or quickly: slip on a sweater; slipped off her shoes.
3.
a. To get loose or free from; elude: slipped his pursuers.
b. To fail to be remembered by: Her name slips my memory.
4.
a. To release, loose, or unfasten: slip a knot.
b. To unleash or free (a dog or hawk) to pursue game.
5. To give birth to prematurely. Used of animals.
6. To dislocate (a bone).
7. To pass (a knitting stitch) from one needle to another without knitting it.
n.
Phrasal Verb: 1. The act or an instance of slipping or sliding.
2. An accident or mishap, especially resulting in a fall.
3.
a. An error in conduct or thinking; a mistake.
b. A slight error or oversight, as in speech or writing: a slip of the tongue.
4. Nautical
a. A docking place for a ship between two piers.
b. A slipway.
5. Nautical The difference between a vessel's actual speed through water and the speed at which the vessel would move if the screw were propelling against a solid.
6.
a. A woman's undergarment of dress length with shoulder straps.
b. A half-slip.
7. A pillowcase.
8. Geology
a. A smooth crack at which rock strata have moved on each other.
b. A small fault.
c. The relative displacement of formerly adjacent points on opposite sides of a fault.
9. The difference between optimal and actual output in a mechanical device.
10. Movement between two parts where none should exist, as between a pulley and a belt.
11. A sideways movement of an airplane when banked too far.
slip away
Idioms: 1. To depart without being noticed: We slipped away before the presentation was over.
2. To die gradually or peacefully.
3. To disappear or become unavailable: Don't let the opportunity slip away.
give (someone) the slip Slang
To escape the pursuit of.
let slip
To say inadvertently.
slip one over on Informal
To hoodwink; trick.
[Middle English slippen, probably of Middle Low German or Middle Dutch origin; see lei- in the Appendix of Indo-European roots.]