de-lu'-zhun: (1) Isa 66:4, "I also will choose their delusions" (the Revised Version, margin "mockings"), Hebrew ta`alulim, which occurs only here and Isa 3:4 (where it is translated "babes," the Revised Version, margin "childishness"). Its meaning is somewhat ambiguous. The best translation seems to be "wantonness," "caprice." "Their wanton dealing, i.e. that inflicted on them" (BDB). Other translations suggested are "insults" (Skinner), "freaks of fortune" (Cheyne), "follies" (Whitehouse). Septuagint has empaigmata, "mockings," Vulgate (Jerome's Latin Bible, 390-405 A.D.) illusiones. (2) 2Th 2:11 the King James Version, "God shall send them strong delusion" (the Revised Version (British and American) "God sendeth them a working of error"), plane, "a wandering," "a roaming about," in the New Testament "error" either of opinion or of conduct.
⇒See the definition of delusion in the KJV Dictionary
D. Miall Edwards