risus sardonicusn.

1621 P. Heylyn Microcosmus 237 Here [sc. in Sardinia] is..an hearbe, which if one eate he shall die with laughter. Whence came the proverbe, Risus Sardonicus. The truth of this report I will not oppugne, though it be by others more probably coniectured, that the hearbe being of a poysonous nature, causeth men to dye with such a convulsion or contraction of their sinewes, that they seeme to grinne or laugh.

1664 G. Havers tr. T. Renaudot et al. Gen. Coll. Disc. Virtuosi France xxiv. 149 We see a Convulsion causeth the same motion of the Muscles of the Face that Laughter doth; whence cometh that malady which is called Risus Sardonicus, in which, by the retraction of the Nerves towards their Original, the Patient seemes to laugh as he dyes.

1736 Beeriad 55 (note) Risus Sardonicus or Sardonian Laughter, being a Convulsive distortion of the muscles of the Face, causing an involuntary shew of Laughter.

1796 E. Darwin Zoonomia II. 199 The corners of the mouth are frequently retracted into a disagreeable smile, called risus Sardonicus.

1837 Todd's Cycl. Anat. & Physiol. II. 6/2 The countenance in all such cases assumes the peculiar expression or grin called risus Sardonicus.

1876 J. S. Bristowe Treat. Theory & Pract. Med. ii. iv. 514 Tetanic spasms and risus sardonicus have also occasionally been noticed in cases of rheumatic pericarditis.

1948 S. J. Perelman Westward Ha! vii. 86 As the diner stiffened slowly in his chair, his features settling into the ghastly smile known as the risus sardonicus, the waiter administered the coup de grâce, a savory contrived of a moldy sardine spread-eagled on a bit of blackened toast.

2000 Archaeology July–Aug. 52/2 After I had spoken for about four minutes, she lapsed into what appeared to be a deep coma, her mouth gaping open in a frightening grin that resembled risus sardonicus, a rare disease wherein the mouth is distorted into a permanent smile.