From the second edition (1989):
Also 2 unde, 6 vnd. [a. OF. unde, or ad. L. unda wave.]

A wave; Her., a wave-like marking. (Cf. undee a.)

c1200 Trin. Coll. Hom. 177 Ðe water stremes on-heueden up here undes [L. fluctus]. 1490 Caxton Eneydos ii. 15 By troblous reuolucyons of the vndes or wawes [they] were broughte into the Ile of Anchandron. 1592 W. Wyrley Armorie 12 John Basset of new place‥left the Labell, and charged the blacke vnds with manie besants dispersed all ouer them. [1694 Motteux Rabelais 249 Lute, Unds and Sands did long our March oppose.]