gyromancy (n.) Look up gyromancy at Dictionary.com
1550s, method of divination by walking in a circle till the person falls down 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 gyre) + 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, 1856, invented and named in French 1852 by Foucault, from Greek gyros "circle" (see gyre) + skopos "watcher" (see scope (n.1)), because the device demonstrates that the earth rotates.
gyroscopic (adj.) Look up gyroscopic at Dictionary.com
1871, from gyroscope + -ic. Related: Gyroscopically.
gyrostat (n.) Look up gyrostat at Dictionary.com
1879, from gyro- + -stat.
gyrostatics (n.) Look up gyrostatics at Dictionary.com
branch of dynamics dealing with rotating bodies, 1883, from gyrostatic (1879); see gyrostat + -ics.
gyrus (n.) Look up gyrus at Dictionary.com
convolution between grooves, 1842, from Latin gyrus "circle, circuit, career," from Greek gyros "ring, circle" (see gyre).