lad·der 
(lădər)
(lădər)n.
1.
a. An often portable structure consisting of two long sides crossed by parallel rungs, used to climb up and down.
b. Something that resembles this device, especially a run in a stocking.
2.
a. A means of moving higher or lower, as in a hierarchy: used his accomplishments as a ladder to success.
b. A series of ranked stages or levels: high on the executive ladder.
3. A fish ladder.
4. Sports
a. An athletic workout in which one does progressively longer intervals followed by progressively shorter intervals.
b. One of the intervals in such a workout.
intr.v. lad·dered, lad·der·ing, lad·ders
To run, as a stocking does.
[Middle English, from Old English hlǣder; see klei- in the Appendix of Indo-European roots.]