• (America) IPA: /ɪnˈdɛv.ɚ/
• (RP) IPA: /ɪnˈdɛv.ə/

endeavour (plural endeavours)

1. Standard spelling of endeavor
   • 1640, Thomas Hobbes, chapter 28, in The Elements of Law, part II:

     And these three: 1. the law over them that have sovereign power; 2. their duty; 3. their profit: are one and the same thing contained in this sentence, Salus populi suprema lex; by which must be understood, not the mere preservation of their lives, but generally their benefit and good. So that this is the general law for sovereigns: that they procure, to the uttermost of their endeavour, the good of the people.

endeavour (endeavours, present participle endeavouring; simple past and past participle endeavoured)

1. Standard spelling of endeavor
   • 1711 May, [Alexander Pope], An Essay on Criticism, London: […] W[illiam] Lewis […]; and sold by W[illiam] Taylor […], T[homas] Osborn[e] […], and J[ohn] Graves […], →OCLC ↗:

     And such were Prais'd who but endeavour'd well.

   • November 20, 1777, William Pitt, 1st Earl of Chatham, Debate in the Lords on the Address of Thanks

     It is our duty […] to endeavour the recovery of these most beneficial subjects.

   • 1669 May 18, Sir Isaac Newton, Letter (to Francis Aston):

     If you be affronted, it is better, in a foreign country, to pass it by in silence, and with a jest, though with some dishonour, than to endeavour revenge; for, in the first case, your credit's ne'er the worse when you return into England, or come into other company that have not heard of the quarrel.