enormousyoudaoicibaDictYouDict[enormous 词源字典]
enormous: [16] Etymologically, enormous is a parallel formation to abnormal and extraordinary. It comes from Latin ēnormis, a compound adjective formed from the prefix ex- ‘out of’ and norma ‘pattern, rule’ – hence literally ‘out of the usual pattern’. It originally had a range of meanings in English, including ‘abnormal, unusual’ (‘entered the choir in a military habit, and other enormous disguises’, Thomas Warton, History of English Poetry 1774) and ‘outrageous’.

By the beginning of the 19th century these had mostly died out, leaving the field clear for modern English ‘huge’, although the notion of ‘outrageousness’ remains in the noun derivative enormity [15].
=> abnormal, normal[enormous etymology, enormous origin, 英语词源]
enormous (adj.)youdaoicibaDictYouDict
1530s, "abnormal" (usually in a bad sense), from Latin enormis "out of rule, irregular, shapeless; extraordinary, very large," from assimilated form of ex- "out of" (see ex-) + norma "rule, norm" (see norm), with English -ous substituted for Latin -is. Meaning "extraordinary in size" is attested from 1540s; original sense of "outrageous" is more clearly preserved in enormity. Earlier was enormyous (mid-15c.) "exceedingly great, monstrous." Related: Enormously; enormousness.