slapdash (adv.)youdaoicibaDictYouDict[slapdash 词源字典]
1670s, from slap (v.) + dash (v.). As an adjective, "dashing, offhand, careless," from 1792. As a noun, "rough-coat, coarse plaster," from 1796.[slapdash etymology, slapdash origin, 英语词源]