isorrhythmic

from The Century Dictionary.

• In ancient prosody, having the same number of moræ or units of time in thesis and arsis: as, an isorrhythmic measure or foot; characterized by such proportion (1:1) of thesis and arsis: as, the isorrhythmic class of feet; isorrhythmic movement. The isorrhythmic class (of feet) consists of the tetrasemic feet, namely: the dactyl , the anapest , and the spondee .