Definition of "constant"

The constant pinging of electronic devices is driving many people to the end of their tether. Electronic devices not only overload the senses and invade leisure time. They feed on themselves: the more people tweet the more they are rewarded with followers and retweets.

2013 November 16, Schumpeter, “The mindfulness business”, in The Economist, volume 409, number 8862

Both loving one fair maid, they yet remained constant friends.

c. 1580 (date written), Philippe Sidnei [i.e., Philip Sidney], “[The Second Booke] Chapter 3”, in Fulke Greville, Matthew Gwinne, and John Florio, editors, The Countesse of Pembrokes Arcadia [The New Arcadia], London: […] [John Windet] for William Ponsonbie, published 1590; republished in Albert Feuillerat, editor, The Countesse of Pembrokes Arcadia (Cambridge English Classics: The Complete Works of Sir Philip Sidney; I), Cambridge, Cambridgeshire: University Press, 1912, page 162

I am constant to my purposes.

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene ii]

His gifts, his constant courtship, nothing gained.

1700, [John] Dryden, “Theodore and Honoria, from Boccace”, in Fables Ancient and Modern; […], London: […] Jacob Tonson, […]

If […] you mix them, you may turn these two fluid liquors into a constant body.

1659 December 30 (date written), Robert Boyle, New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects, (Made, for the Most Part, in a New Pneumatical Engine) […], Oxford, Oxfordshire: […] H[enry] Hall, printer to the University, for Tho[mas] Robinson, published 1660

I am no more mad than you are: make the trial of it with any constant question.

c. 1601–1602 (date written), William Shakespeare, “Twelfe Night, or What You Will”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act IV, scene ii]