v. Obs. [UNDER adv.] trans. To grind by pressing on (something placed below).

1

1598.  Sylvester, Du Bartas, II. i. III. Furies, 731. Like falling Towers o’rturned by the winde, That break themselves on that they under-grinde. Ibid. (1608), iv. IV. Decay, 847. As with his weight, a hollow Rocky-Hill … Shivers it selfe on stones it under-grindes.

2