main ingredients; chief materials
Used in contexts like cooking, manufacturing, or construction to refer to the primary components of something.
The main ingredients of this dish are tofu and vegetables.
Wood is used as the chief material for the construction.
Compound of 主 (しゅ, 'main') and 材 (ざい, 'material'). The reading is on'yomi, and the word is a straightforward Sino-Japanese compound.