Refers to the projecting part of a container (teapot, kettle, watering can, etc.) from which liquid is poured.
Pour tea from the spout of the teapot.
The spout of the kettle got chipped.
Standard spelling.
Irregular okurigana usage; less common.
Compound of 注ぎ (tsugi, the continuative form of 注ぐ 'to pour') + 口 (kuchi 'mouth, opening').