Why are rats called rats? - briefly
The term derives from Old English ræt, which was borrowed from Latin rattus meaning “the common rodent.” It was applied to these ubiquitous mammals because the word already identified the species recognized for its size and behavior.
Why are rats called rats? - in detail
The name “rat” derives from the Old English word ræt or ræt, which itself traces back to the Proto‑Germanic rattaz. This root is shared with Old Norse rǫt and German Ratte, indicating a common ancestral term for the animal. The Proto‑Indo‑European source is reconstructed as *reh₂t‑, a lexical element meaning “rodent” or “small pest”.
During the Middle Ages, the word entered Middle English as ratte, retaining the original meaning of a small, long‑tailed mammal belonging to the genus Rattus. The spelling stabilized to “rat” in Early Modern English, while the scientific classification later formalized the genus name Rattus in the 18th‑century Linnaean system.
Key factors that reinforced the usage of this term include:
- Consistent reference to the animal’s characteristic size and behavior across Germanic languages.
- Adoption by scholars and naturalists who applied the Latinized form Rattus when describing species such as the brown rat (Rattus norvegicus) and the black rat (Rattus rattus).
- Persistence in vernacular speech, where “rat” became the default label for any member of the family Muridae that matched the typical urban pest profile.
Thus, the modern English label reflects a continuous linguistic lineage from ancient Germanic roots, reinforced by scientific nomenclature and everyday usage.