commensurable

a. [ L. commensurabilis; pref. com- + mensurable. See Commensurate, and cf. Commeasurable. ] Having a common measure; capable of being exactly measured by the same number, quantity, or measure. -- Com*men"su*ra*ble*ness, n. [1913 Webster]

Commensurable numbers or
Commensurable quantities (Math.), those that can be exactly expressed by some common unit; thus a foot and yard are commensurable, since both can be expressed in terms of an inch, one being 12 inches, the other 36 inches. --
Numbers commensurable in power, or
Quantities commensurable in power, those whose squares are commensurable. [1913 Webster]