Capable of fluctuating; able to vary, change, or move back and forth.
From 'fluctuate' plus the suffix '-able' meaning capable of or able to. This follows the standard English pattern for creating adjectives that describe what something can do.
Fluctuable temperatures, fluctuable emotions, fluctuable market prices—anything that moves up and down could theoretically be called fluctuable, though most people just say 'varies' or 'changes.'
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