Unthinkable

a. and sb. [UN-¹ 7 b.]

  1.  Too great, numerous, etc., to be conceived or apprehended by thought; unimaginable.

c. 1430.  Life St. Kath. (1884), 48. Þey sawe al þe prison ful of vnthencable and vnspecable swetnesse of sauour.

a. 1450.  Myrr. our Ladye, 183. Wherfore the nombre of crownes is to be beleued vnthyncable.

1526.  Pilgr. Perf. (W. de W., 1531), 28 b. He hath gyuen … treasour spirituall whiche be in valour vnthynkable.

1623.  Lisle, Ælfric on O. & N. Test., p. xxiv. The losse whereof is vnspeakeable, vnthinkable, vnsufferable misery.

1674.  N. Fairfax, Bulk & Selv., 193. The unthinkable care and forecast in all its evennesses and entwinings.

1879.  M. Pattison, Milton, 112. The bathos is unthinkable.

1897.  Westm. Gaz., 6 July, 2/1. You wander … in cool glades of unthinkable beauty.

  2.  Incapable of being framed or grasped by thought; incogitable.

c. 1445.  Pecock, Donet, 84. A þing fer aboue alle creaturis þouȝt vnþenkable.

c. 1530.  trans. Erasmus’ Serm. Ch. Jesus (1901), 7. Jesus, whiche by an vnspeakable, nay, with an vnthynkable reason, is borne God of God.

1830.  W. Taylor, Hist. Surv. Germ. Poetry, I. 453. Separate from her To live is quite unthinkable—is death.

1884.  H. Spencer, in Contemp. Rev., July, 33. From whatever point of view we consider it, Bentham’s proposition proves to be unthinkable.

  absol. and sb.  1871.  Jowett, Plato, III. 134. The negative of measure or limit; the unthinkable, the unknowable; of which nothing can be affirmed.

1897.  F. H. Balfour (title), Unthinkables.

  Hence Unthinkably adv.

1526.  Pilgr. Perf. (W. de W., 1531), 244 b. The paynes y^t he suffred … excedeth vnthynkably all the paynes that ony creature myght suffre.

1895.  Young England, XVI. 30/1. Our hearths are warmed by the stored-up sunshine of unthinkably distant ages.