before vowels ferr-, word-forming element indicating the presence of or derivation from iron, from Latin ferro-, combining form of ferrum "iron," which is of unknown origin. Possibly of Semitic origin, via Etruscan [Klein]; Watkins suggests "possibly borrowed (via Etruscan) from the same obscure source as OE bræs "brass." Also sometimes especially indicative of the presence of iron in the ferrous state; ferri- indicating iron in the ferric state.
1610s, literal, "having the properties of a magnet;" 1630s, figurative, "having powers of attraction;" from Modern Latin magneticus, from Latin magnes (see magnet). Meaning "capable of being attracted by a magnet" is by 1837. Related: Magnetical (1580s); magnetics "the science of magnetism" (1786).
<a href="https://www.etymonline.com/word/ferromagnetic">Etymology of ferromagnetic by etymonline</a>
Harper, D. (n.d.). Etymology of ferromagnetic. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/ferromagnetic