Commensurable \Com*men"su*ra*ble\, 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.

Commensurable numbers or 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, or Quantities, commensurable in power, those whose squares are commensurable.

Source: Webster's Revised Unabridged Dictionary (1913)