Definition of "gyri" [‖Gy•ri]

• Plural of gyrus. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Outermost, covering the entire cerebrum, is the gray matter, the cerebral cortex, an eighth-inch-thick landscape of rolling hills (known as gyri) and valleys (sulci)."
• "The ridges of cerebral tissue between the sulci, which look like softly rolled matter that has been flattened out slightly by the pressure of the skull, are called gyri (j'y'ry; "rolls" L), the singular form being gyrus (jy'rus)."
• "The lateral surface of the frontal lobe (Fig. 726) is tranversed by three sulci which divide it into four gyri: the sulci are named the precentral, and the superior and inferior frontal; the gyri are the anterior central, and the superior, middle, and inferior frontal."