HackerVoca

circumspect, cautious, wary
wave : undulate /verb [intransitive]
formal to move or be shaped like waves that are rising and falling: undulating hills
undulation noun [countable, uncountable] , fluctuate / / verb [intransitive]
if something such as a price or amount fluctuates, it changes very often from a high level to a low one and back again
[+ between]: The present output of oil fluctuates between 3 and 5 million gallons per week. | fluctuate wildly: House prices fluctuated wildly in the 80s.

weak : fragile, frail, delicate, feeble
weaken : enfeeble, undermine, deplete / / verb [transitive usually passive]
to reduce the amount of something that is available: Our food reserves had been severely depleted over the winter.
depletion / noun [uncountable]: the depletion of the ozone layer
, diminish, lessen, lower, reduce, impair, minimize
weakness : flaw, defect, fault