'Psychrometer' definitions:

Definition of 'psychrometer'

(from WordNet)
noun
A hygrometer consisting of a dry-bulb thermometer and a wet-bulb thermometer; their difference indicates the dryness of the surrounding air

Definition of 'Psychrometer'

From: GCIDE
  • Psychrometer \Psy*chrom"e*ter\, n. [Gr. psychro`s cold + -meter: cf. F. psychrom[`e]tre.] An instrument for measuring the tension of the aqueous vapor in the atmosphere, being essentially a wet and dry bulb hygrometer. [1913 Webster]