tur·tle·back /ˈtɝtḷˌbæk/ 龜甲,龜甲甲板
Tur·tle·back n. 1. Archaeol. A rude stone celt of a form suggesting the back of a turtle. 2. Naut. A convex deck at the bow or stern of a vessel, so made to shed the seas quickly. ◄ ►