a combining form with the meanings âheight,â âtip end,â âextremities of the body,â used in the formation of compound words: acrophobia. Also, especially before a vowel, acr-. Origin of acro-. < Greek, combining form of Ã¡kros topmost, highest; akin to Latin Äcer sharp.
â¢ CANTUS FIRMUS (noun) The noun CANTUS FIRMUS has 1 sense: 1. a melody used as the basis for a polyphonic composition. Familiarity information: CANTUS FIRMUS used as a noun is very rare. Dictionary entry details.
The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles). The medial portion of the ring also encompasses the optic foramen through which the optic nerve and ophthalmic artery pass.