Third person singular present tense of disproportionate; to make unbalanced or to lack proper proportion.
From disproportionate (verb form) + -s (third person singular). The verb form of disproportionate allows it to describe the action of making something unbalanced.
Most people don't realize that 'disproportionate' can be used as a verb, but it can—you can 'disproportionate' a design by adding an enormous feature, though this usage is quite rare.
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