1.
bottom surface; base; underside
The lowest surface of an object, container, or geometric shape. Used both in everyday contexts (the bottom of a box) and in mathematics (the base of a solid figure).
箱の底面に名前を書く。
To write one's name on the bottom of the box.
底面の面積を求めなさい。
Calculate the area of the base.
この円柱の底面は半径五センチの円である。
The base of this cylinder is a circle with a radius of five centimeters.
Composed of 底 (bottom) and 面 (surface, face). Used in both everyday and mathematical/technical contexts.
COMMON COLLOCATIONS:
- 底面の面積: area of the base
- 底面積: base area
- 底面が平ら: the bottom is flat
- 底面に滑り止め: non-slip on the bottom
SIMILAR WORDS:
- 底: bottom — more casual and general; the bottom of a bag, ocean, etc.
- 裏面: reverse side / back — the opposite side of a flat object, not necessarily the bottom
- 下面: lower surface — the underside, similar but less common
NOTE:
In mathematics, 底面 specifically refers to the base of a three-dimensional figure such as a prism, cylinder, or pyramid. This is a common term in Japanese math education.