n. The depression between two ridges of a tooth, typically shown in such molars as those of the tapir and mastodon: correlated with lake, which is a depression surrounded by a raised ridge of enamel such as occurs in the molars of a horse.n. A depression, or a relatively low and somewhat level area, more or less completely inclosed by hills or mountains; the basin of a stream of any size, or the area drained by it, and, in accordance with more general usage, the part of that area which lies near the stream and is not much raised above its level.n. Hence, any similar depression of any size.n. Specifically, in architecture, the internal angle formed by the meeting of two inclined sides of a roof.