Translation guide
The bottom surface or lower part of something, often hidden from view. In Japanese, the most common word is 裏側 (uraside), but other terms are used depending on context, such as 下側 (lower side) or 底面 (bottom surface).
Referring to the physical underside of something, like a table, leaf, or vehicle.
General term for the reverse side or underside of something. Often implies the side not normally seen.
There's gum stuck to the underside of the table.
There's a bug on the underside of the leaf.
Literally 'lower side'. Used when emphasizing the bottom part of something, often in contrast to the top side.
Please clean the underside of the shelf.
Refers to the bottom surface or base of an object, often used for containers, boxes, or geometric shapes.
There's a notice on the underside of the box.
Technical or formal term for the lower surface, used in engineering or architecture.
Inspect the underside of the bridge.
Metaphorical use, referring to the hidden side of a situation, society, or personality.
Also used metaphorically for the hidden side of things, similar to 'underside' in English.
To know the underside of society.
Literally 'dark part', used for the seedy or hidden underside of something, often with negative connotations.
Literally 'back face', meaning the hidden side of a person or organization.
He has an underside (a hidden side).
Specifically the underside of a car, aircraft, or machinery.
裏側 (uraside) emphasizes the reverse or hidden side, while 下側 (shitagawa) simply means the lower side. Use 裏側 when the underside is not normally visible, and 下側 when contrasting with the top side.
Avoid directly translating 'underside' as 下の面 (shita no men) or 底 (soko) in most contexts. These can sound unnatural. Use the appropriate term based on the object.
歴史の暗部に光を当てる。
Shed light on the underside of history.
飛行機の下面を撮影する。
Photograph the underside of the airplane.