The story
- Proto-Indo-European*h₂er-
- Proto-Indo-European*h₂(e)rmos
- Proto-Italic*armos
- Latinarma
- Latinarmō
- Latinarmātus
- Old Spanisharmado
- Spanisharmado
- Spanisharmadillo
- English todayarmadillo
Borrowed from Spanish armadillo, diminutive of armado (“armored”), in reference to its protective plates.
Etymology from Wiktionary, CC BY-SA 4.0.