Rōach, n.

n. [A-S. *reohha, reohche, hreocce, D. rog, roch, Dan. rokke, Sw. rocka, H. Ger. roche, L. Ger. ruche. Cf. RAY.]

1. (Ichth.) A gregarious fresh-water fish of the carp family (Leuciscus rutilus). It is of a silver-white color, with a greenish back, having the dorsal fin opposite the ventral. It is about a foot in length.
2. (Naut.) The curve or arch cut in the foot of some square sails. Brande.
3. A cockroach.

As sound as a roach, perfectly sound:—a phrase supposed to have been, originally, as sound as a rock. [Fr. roche.]