pliable
Meaning: flexible
Usage: Aircraft wings are designed to be somewhat pliable so they do not break in heavy turbulence.
agile
Meaning: quick, nimble
Usage: The dogs were too slow to catch the agile rabbit.
viscous
Meaning: not free flowing, syrupy
Usage: The viscous syrup took three minutes to pour out of the bottle.
flaccid
Meaning: limp, not firm or strong
Usage: If a plant is not watered enough, its leaves become droopy and flaccid.
oscillate
Meaning: to sway from one side to the other
Usage: The pendulum oscillated precisely to tell the exact time.
undulate
Meaning: to move in waves
Usage: As the storm began to brew, the placid ocean began to undulate to an increasing degree.