- switchblade (n.)
[switchblade 词源字典]
- also switch-blade, type of folding pocket knife, 1932, from switch (n.) + blade. So called for the "switch" which is pressed to spring the knife open. Earlier a similar tool was known as an Arkansas toothpick (1837) and a clasp-knife (1755).[switchblade etymology, switchblade origin, 英语词源]