gyromancy (n.) Look up gyromancy at Dictionary.com
1550s, method of divination said to have been practiced by a person walking in a circle marked with characters or signs till he fell from dizziness, the inference being drawn from the place in the circle at which he fell; from Medieval Latin gyromantia, from Greek gyyros "circle" (see gyro- (n.)) + manteia "divination, oracle" (see -mancy).
gyroscope (n.) Look up gyroscope at Dictionary.com
heavy rotating wheel with an axis free to turn in any direction, 1853, improved and named in French 1852 by Foucault, from Greek gyros "a circle" (see gyre (n.)) + skopos "watcher" (from PIE root *spek- "to observe"), because the device demonstrates that the earth rotates.
gyroscopic (adj.) Look up gyroscopic at Dictionary.com
1869, from gyroscope + -ic. Related: Gyroscopically.
gyrostat (n.) Look up gyrostat at Dictionary.com
instrument for illustrating the dynamics of rotation, 1868, from gyro- + -stat.
gyrostatics (n.) Look up gyrostatics at Dictionary.com
branch of dynamics dealing with rotating bodies, 1883, from gyrostatic (1875); see gyrostat + -ics.
gyrus (n.) Look up gyrus at Dictionary.com
convolution between grooves of the brain, 1827, from Latin gyrus "circle, circuit, career," from Greek gyros "a ring, circle" (see gyre (n.)).