Source : Webster's Revised Unabridged Dictionary (1913)

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.