1A door, especially a Japanese-style sliding door such as shoji or fusuma.
戸を閉めてください。
Please close the door.
台所の戸がきしんでうるさい。
The kitchen door squeaks and is noisy.
古い家には障子や襖などの戸が使われている。
Old houses use doors like shoji and fusuma.
玄関の戸を開けると、猫が飛び出してきた。
When I opened the front door, a cat jumped out.
2A shutter or panel used to close off a window or doorway, as with 雨戸 (rain shutters).
台風が来るので雨戸を閉めた。
We closed the shutters because a typhoon was coming.
夜になると戸を閉めて家中を暗くする。
At night we close the shutters and darken the whole house.
3Archaic: the entrance or gate of a house, seen in classical or literary Japanese.
古い和歌では「家の戸」が家の入り口を意味することが多い。
In old waka poetry, 'ie no to' often means the entrance of a house.
4Archaic: a 'narrows' — a narrow passage or strait, used in older texts for geographic features.
その谷の戸は狭く、進軍が難しかった。
The narrows of that valley were tight, making the advance difficult.