powerful (adj.)youdaoicibaDictYouDict[powerful 词源字典]
c. 1400, from power (n.) + -ful. Meaning "of great quality or number" is from 1811; colloquial sense of "exceedingly" (adv.) is from 1822. Related: Powerfully. Thornton ("American Glossary") notes powerful as "Much used by common people in the sense of very," along with monstrous and cites curious expressions such as devilish good, monstrous pretty (1799), dreadful polite, cruel pretty, abominable fine (1803), "or when a young lady admires a lap dog for being so vastly small and declares him prodigious handsome" (1799).[powerful etymology, powerful origin, 英语词源]
vast (adj.)youdaoicibaDictYouDict
1570s, "being of great extent or size," from Middle French vaste, from Latin vastus "immense, extensive, huge," also "desolate, unoccupied, empty." The two meanings probably originally attached to two separate words, one with a long -a- one with a short -a-, that merged in early Latin (see waste (v.)). Meaning "very great in quantity or number" is from 1630s; that of "very great in degree" is from 1670s. Very popular early 18c. as an intensifier. Related: Vastly; vastness; vasty.