Definition of "monstrous"

So bad a death argues a monstrous life.

c. 1596–1599 (date written), William Shakespeare, “The Second Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act III, scene iii]

The chiding billovv ſeemes to pelt the cloudes, / The vvinde ſhak'd ſurge, vvith high and monſtrous mayne, / Seemes to caſt vvater, on the burning Beare, […]

c. 1603–1604 (date written), William Shakespeare, The Tragœdy of Othello, the Moore of Venice. […] (First Quarto), London: […] N[icholas] O[kes] for Thomas Walkley, […], published 1622, [Act II, scene i], page 21

Possibly monster pumpkins may become still more monstrous by the shoots being ringed, and so may other vegetables and fruits where quality is of less importance than mere size.

1901 December 20, “The Ringing of Plants”, in The Agricultural Journal and Mining Record‎, volume 4, number 21, page 663

The irregular and monstrous births

1689 (indicated as 1690), [John Locke], chapter 3, in An Essay Concerning Humane Understanding. […], London: […] Eliz[abeth] Holt, for Thomas Basset, […]

He, therefore, that refuses to do good to them whom he is bound to love […] is unnatural and monstrous in his affections.

1650, Jeremy Taylor, The rule and exercises of holy living

Where thou, perhaps, under the whelming tide / Visitest the bottom of the monstrous world.

1637, John Milton, “Lycidas”, in Poems of Mr. John Milton, […], London: […] Ruth Raworth for Humphrey Mosely, […], published 1646

The whole story was monstrous, and only worthy of the superstitious days in which it was written.

1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887