平面|へいめんheimen[0]heiban (flat)

1. nounlevel surface; plane

• Related水平すいへいNeutralRefers to a horizontal direction or state with no tilt, as in 「水平に置く」; 「平面」 is a flat surface or a geometric plane.
• Antonym立体りったいNeutralA three-dimensional object or solid; also a multi-storey car park. Opposite of the two-dimensional 「平面」 in dimension.
• Antonym曲面きょくめんNeutralA curved surface; contrasts with 「平面」 in being curved rather than flat.

Use 「平面」 for a flat surface or a two-dimensional geometric plane, as in 「平面図」 and 「平面的」. 「水平」 describes a level, untilted state; 「立体」 and 「曲面」 are its opposites in dimension and curvature.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 平たいらな表面ひょうめんの事こと。
2. 面内めんないのすべての二に点てんを結むすぶ直線ちょくせんが含ふくまれる線せん。
3. 水平面すいへいめん。