noun
front side; obverse
Refers to the front or face of flat objects like paper, coins, or medals. Often contrasted with 裏面 (りめん).
See also: 裏面
コインの表面には鷲の絵が描かれている。
An eagle is depicted on the obverse of the coin.
書類の表面に署名してください。
Please sign on the front side of the document.
noun
A-side
Used for the main side of a vinyl record or cassette tape, typically containing the lead track.
このレコードの表面にはヒット曲が収録されている。
The A-side of this record contains the hit song.
noun
main levels
In video games, refers to the primary stages or content, as opposed to hidden levels or post-game extras.
See also: 裏面
表面のステージをすべてクリアすると、隠しダンジョンが出現する。
Clearing all the main levels unlocks a hidden dungeon.
裏面 means the back or reverse side, the opposite of 表面. It is used for the back of paper, coins, records (B-side), and in gaming for hidden or post-game content.
Compound of 表 (おもて, 'front') and 面 (めん, 'face, surface'). The reading おもてめん is a straightforward combination of these elements.