LA·SIK (l??s?k)n. Eye surgery to correct certain refractive disorders, such as myopia, in which a surface layer of the cornea is temporarily separated and folded back to expose the inner surface for reshaping with a laser.[la(ser-assisted in) si(tu) k(eratomileusis).]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.