defect

Etymology

From Middle French defaicte, from Latin defectus (“a failure, lack”), from deficere (“to fail, lack, literally 'undo'”), from past participle defectus, from de- (“priv.”) + facere (“to do”).

noun

1. A fault or malfunction.
   a defect in the ear or eye; a defect in timber or iron; a defect of memory or judgment
   But ever since the concept of "hamartia" recurred through Aristotle's Poetics, in an attempt to describe man's ingrained iniquity, our impulse has been to identify a telling defect in those brought suddenly and dramatically low. 21 October 2014, Oliver Brown, “Oscar Pistorius jailed for five years – sport afforded no protection against his tragic fallibilities”, in The Daily Telegraph (Sport)
   Another major defect of the current literature dealing with the nomenclature of hybrid forms of English is the scant attention paid to the question of frequency. 2018, James Lambert, “A multitude of ‘lishes’: The nomenclature of hybridity”, in English World-Wide, page 4
2. The quantity or amount by which anything falls short.
   and the indefatigable application with which they have supplied the defects of early culture. 1824, Lydia Sigourney, Sketch of Connecticut
3. (mathematics) A part by which a figure or quantity is wanting or deficient.

verb

1. (intransitive) To abandon or turn against; to cease or change one's loyalty, especially from a military organisation or political party.
   Capitalizing on the restive mood, Mr. Farage, the U.K. Independence Party leader, took out an advertisement in The Daily Telegraph this week inviting unhappy Tories to defect. In it Mr. Farage sniped that the Cameron government — made up disproportionately of career politicians who graduated from Eton and Oxbridge — was “run by a bunch of college kids, none of whom have ever had a proper job in their lives.” May 23 2013, Sarah Lyall, “British Leader’s Liberal Turn Sets Off a Rebellion in His Party”, in New York Times, retrieved 2013-05-29
2. (military) To desert one's army, to flee from combat.
3. (military) To join the enemy army.
4. (law) To flee one's country and seek asylum.
   Passing through Thailand, she submitted a handwritten statement agreeing to defect, a requirement for North Korean refugees to be allowed to enter the South. 15 August 2015, Choe Sang-Hun, “A North Korean Defector’s Regret”, in The New York Times, retrieved 2015-09-20