A coal-iron compound or substance in alchemical and early metallurgical terminology.
From anthracis + martus (Latin-influenced form related to Mars/iron). This quasi-Latin neologism reflects the synthetic language of medieval alchemy.
Anthracomartus is probably the most obscure word in this entire list—it exists mainly in footnotes of medieval alchemy texts, representing substances these proto-scientists couldn't fully explain but desperately wanted to name.
Complete word intelligence in one call. Free tier — 50 lookups/day.