Opsiometer
Pronunciation : Op`si*om"e*ter
Part of Speech : n.
Etymology : [Gr. -meter: cf. F. opsiom?tre.]
Definition : Defn: An instrument for measuring the limits of distincts vision in different individuals, and thus determiming the proper focal length of a lens for correcting imperfect sight. Brande & C.
Source : Webster's Unabridged Dictionary, 1913