castors is a form of:

Castor




SEE: Caster, a small wheel
noun
1.
A substance having a strong, penetrating small, secreted by glands in the groin of the beaver, the castoroil plant. -castor bean the seed of castor oil plant, the castor oil plant. -castor oil a colorless to pale yellow, viscid liquid obtained from the កង់សម្រាប់ភ្ជាប់ជើងតុ, រនេលមានកង់, អ្នកលក់ឬអ្នកធ្វើប្រេង
ENGLISH MEANING
noun
1.
A genus of rodents, including the beaver.
2.
A hat, esp. one made of beaver fur; a beaver.
3.
A heavy quality of broadcloth for overcoats.
4.
The northernmost of the two bright stars in the constellation Gemini, the other being Pollux.
1.
Castoreum