All 3 Uses

agitate
in
To Build a Fire
(Auto-generated)

Each time he had pulled a twig he had communicated a slight agitation to the tree—an imperceptible ----------, so far as he was concerned, but an ---------- sufficient to bring about the disaster.
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agitation = shaking
Each time he had pulled a twig he had communicated a slight agitation to the tree—an imperceptible agitation, so far as he was concerned, but an agitation sufficient to bring about the disaster.†

agitation = the act of stirring up (emotionally or physically); or a state of emotional unrest
Each time he had pulled a twig he had communicated a slight agitation to the tree—an imperceptible agitation, so far as he was concerned, but an agitation sufficient to bring about the disaster.†

Definitions:

(1) (agitate)
to stir up or shake -- emotionally (as when people are angered or upset) or physically (as when a washing machine cleans clothes)
(2) (meaning too rare to warrant focus)