The quality or state of being commensurate; the ability to be measured by the same standard or compared fairly.
From commensurate (having the same measure) plus the suffix -ability. Ultimately from Latin mensura (measure), with the prefix com- (with/together).
In mathematics, the commensurability of numbers is crucial—whole numbers and fractions are commensurable, but the diagonal of a square to its side are incommensurable, blowing ancient Greek minds.
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