Another bout of idle wondering led me to look up the etymology of stamina; I suddenly realized it looked like the plural of stamen, but thought “that can’t be right.” As it turns out, it is, in an unexpected way. Before stamen meant “The male or fertilizing organ of a flowering plant,” it meant ‘the warp in an upright loom’ (the Latin word stāmen is from the Proto-Indo-European root *stā- ‘stand’), and from there it came to mean (in the OED’s words) “The thread spun by the Fates at a person’s birth, on the length of which the duration of his life was suppose[d] to depend. Hence, in popular physiology, the measure of vital impulse or capacity which it was supposed that each person possessed at birth, and on which the length of his life, unless cut short by violence or disease, was supposed to depend.” (1709 Tatler No. 15.1 “All, who enter into human life, have a certain date or Stamen given to their being, which they only who die of age may be said to have arrived at”; 1753 L. M. Accompl. Woman I. 246 “Bad example hath not less influence upon education than a bad stamen upon the constitution.”) Hence the plural stamina meant “The congenital vital capacities of a person or animal, on which (other things being equal) the duration of life was supposed to depend; natural constitution as affecting the duration of life or the power of resisting debilitating influences” (1701 C. WOLLEY Jrnl. New York 60 “Such as have the natural Stamina of a consumptive propagation in them”; 1823 GILLIES Aristotle’s Rhet. I. v. 180 “If the stamina are not sound, disease will soon ensue”), and finally the modern sense “Vigour of bodily constitution; power of sustaining fatigue or privation, of recovery from illness, and of resistance to debilitating influences; staying power” (1726 SWIFT Let. Sheridan 27 July Wks. 1841 II. 588/1, “I indeed think her stamina could not last much longer when I saw she could take no nourishment”). This was originally construed as a plural, but by the nineteenth century careless writers were using it as a singular (1834 M. SCOTT Cruise Midge viii, “Why, Sir Oliver, the man is exceedingly willing,.. but his stamina is gone entirely”), and this rapidly became standard. Heretofore, when encountering people who insist that data should take a plural verb, I have said “I presume, then, you feel the same about agenda“; I will now add stamina to my arsenal.