The Collaborative International Dictionary
Mensurable \Men"su*ra*ble\, a. [L. mensurabilis, fr. mensurare to measure, fr. mensura measure: cf. F. mensurable. See Measurable, Measure.] Capable of being measured; measurable.
Douglas Harper's Etymology Dictionary
c.1600, from Late Latin mensurabilis "that which can be measured," from mensurare "to measure" (see measure (v.)). Related: Mensurably; mensurability.
a. 1 measurable 2 (context music English) Having a fixed rhythm.