noun
brain tonic; nootropic
A medicinal or supplemental agent intended to improve brain function, memory, or mental clarity. Often used in health and supplement contexts.
この健脳剤は集中力を高めると言われている。
This brain tonic is said to improve concentration.
Compound of 健 (healthy), 脳 (brain), and 剤 (medicine/agent). The exact historical derivation is uncertain, but the word is a modern coinage likely from medical or supplement terminology.