What is "lactometer"

Lactometer \Lac*tom"e*ter\, n. [L. lac, lactis, milk + meter: cf. F. lactom[`e]tre. Cf. Galactometer.] An instrument for estimating the purity or richness of milk, as a measuring glass, a specific gravity bulb, or other apparatus.

n. A device that estimates the cream content of milk by measuring its specific gravity.