noun
adhesive; bonding agent
Technical term for a substance used to join materials together, such as glue or cement.
この接合剤は金属とプラスチックの接着に適している。
This adhesive is suitable for bonding metal and plastic.
接着剤 is the more common everyday word for glue or adhesive; 接合剤 is a technical term often used in engineering or manufacturing contexts.
Compound of 接合 (setsugō, 'joining, bonding') + 剤 (zai, 'agent, chemical'). The exact historical derivation is uncertain, but the word follows a standard technical compound pattern.