noun, noun which may take the genitive case particle 'no', na-adjective
same quality; homogeneous; of the same nature
Describes things that share essential characteristics, composition, or nature. Often used in formal, academic, or analytical contexts.
These two products are made of the same quality material.
Their opinions are homogeneous.
同質 means 'of the same nature/homogeneous', the direct opposite of 異質's 'different in nature/heterogeneous'.
Compound of 同 (same) and 質 (quality, nature). The reading is on'yomi, consistent with Sino-Japanese vocabulary.