ferrea
ferrea is a Latin form of ferreus, meaning “made of iron; hard, cruel”. It is the ablative singular feminine adjective.
Found 67 times in the Latin texts on Socratos.
Where it is used
Caesar, De Bello Civili 1.58: … Itaque, dum locus comminus pugnandi daretur, aequo animo singulas binis navibus obiciebant atque iniecta manu ferrea et retenta utraque nave diversi pugnabant atque in hostium naves transcendebant et magno numero Albicorum et …
Ovid, Amores 1.1.28: Ferrea cum vestris bella valete modis!
All forms of ferreus (declension table)
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Lewis & Short, A Latin Dictionary (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.