sac·cade (să-käd, sə-)
A rapid intermittent eye movement, as that which occurs when the eyes fix on one point after another in the visual field.
[French, jerk, jolt, from Middle French, from Old French dialectal saquer, to jerk, pull, variant of Old French sachier, to pull forcefully, turn over, shake up, from sac, sack (perhaps in reference to the shaking of bags of wheat to settle their contents); see SAC1.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.