extended form of wack, by 1971.
"crazy person," 1938, back-formation from wacky. Adjective in slang sense of "worthless, stupid," is attested from late 1990s.
updated on March 21, 2014
英语词源词典收录了45867条英语词源词条，基本涵盖了全部常用英语词汇的起源、历史，是研究英语词汇或通过词源学英语的必备工具。