Definition of "pernicious"

Ang. Belieue me on mine Honor, My words expreſſe my purpoſe. Iſa. Ha? Little honor, to be much beleeu'd, And moſt pernitious purpoſe: Seeming, ſeeming. I will proclaime thee Angelo, looke for't.

c. 1603–1604 (date written), William Shakespeare, “Measure for Measure”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene iv], page 70, column 1

[…] her health also having suffered by the change, she immediately, when told of Douglas's projected departure from India, felt the strongest desire to accompany him; and to which Colonel Melbourne the more readily consented, having with reluctance yielded to her request of quitting England, willing as he had been to sacrifice the enjoyment of her society rather than that she should submit to the disadvantages attendant upon a residence in a clime usually found so pernicious to the female constitution.

1838, [Letitia Elizabeth] Landon (indicated as editor), chapter XVIII, in Duty and Inclination: […], volume III, London: Henry Colburn, […], page 231

Puritanism no longer employs the thumbscrew and lash; but it still has a most pernicious hold on the minds and feelings of the American people.

1911, Emma Goldman, “The Hypocrisy of Puritanism”, in Anarchism and Other Essays

In January, the company laid off a third of its staff and renounced ads as a pernicious influence on the world, without mentioning that Google and Facebook are so good at ads there’s hardly room for anyone else to compete.

2017 March 22, Jacob Kastrenakes, “Medium launches memberships for $5 per month”, in The Verge‎

A man has always been a woman’s best excuse to avoid her destiny; that a man is her destiny is one of patriarchy’s most pernicious tenets. What a scam.

2019 July 9, Toni Bentley, “What Do the Sex Lives of ‘Three Women’ Tell Us About Female Desire?”, in New York Times‎