This is a cut and paste from the OED.
gry , sb. Obs.

a. L. gry (in Plautus Most. i. iii. 67 where recent edd. have gru), a. Gr. gru occurring in
the phrase oude gru, and explained by the lexicographers as meaning (1) the grunt of a pig, (2) the
dirt under the nail; hence the veriest trifle.
The smallest unit in Locke's proposed decimal system of linear measurement, being the tenth of a
line, the hundredth of an inch, and the thousandth of a ('philosophical') foot.
Also means "to roar".