noun
base (logarithm, exponential, number system); radix
Technical term in mathematics for the base of a logarithm, exponential function, or number system.
10を底とする対数を常用対数という。
A logarithm with base 10 is called a common logarithm.
noun
base (triangle, cone, cylinder, etc.)
Geometric term for the base of a shape, such as the bottom side of a triangle or the circular face of a cone or cylinder.
三角形の底辺の長さを測る。
Measure the length of the base of the triangle.
noun
Rare, somewhat literary use to indicate a category, nature, or degree. More commonly expressed with 種類, 程度, or 性質 in modern Japanese.
この底の話は初めて聞いた。
I've never heard this kind of story before.