protagon

From proto- +‎ Ancient Greek ἀγών (agṓn, “a contest”). See protagonist. So called because it was the first definitely ascertained principle of the brain.

protagon (countable and uncountable, plural protagons)

1. (biochemistry) A supposed crystalline molecule that forms the brain. The idea was proposed by Matthias Eugen Oscar Liebreich and Johann Ludwig Wilhelm Thudichum later disproved it, showing that the brain contains various lipids.

• “protagon”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “protagon, noun.”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.