Webster's 1913 Dictionary
PLANIMETER
Pla *nim "e *ter, n. Etym: [Plani- + -meter. Cf. Planometer. ]
Defn: An instrument for measuring the area of any plane figure, however irregular, by passing a tracer around the bounding line; a platometer.
New American Oxford Dictionary
planimeter
pla nim e ter |pləˈnimitər pləˈnɪmɪdər | ▶noun an instrument for mechanically measuring the area of a plane figure. DERIVATIVES plan i met ric |ˌplānəˈmetrik |adjective, plan i met ri cal ly |-ˈmetrik (ə )lē |adverb, pla nim e try |-ˈnimətrē |noun ORIGIN mid 19th cent.: from French planimètre, from Latin planus ‘level ’ + -mètre ‘(instrument ) measuring. ’
Oxford Dictionary
planimeter
planimeter |pləˈnɪmɪtə | ▶noun an instrument for mechanically measuring the area of a plane figure. DERIVATIVES planimetric |-ˈmɛtrɪk |adjective, planimetrically |-ˈmɛtrɪk (ə )l |adverb, planimetry noun ORIGIN mid 19th cent.: from French planimètre, from Latin planus ‘level ’ + -mètre ‘(instrument ) measuring ’.
Duden Dictionary
Planimeter
Pla ni me ter Substantiv, Neutrum Geometrie , das |Planim e ter |zu lateinisch planus (plan ) und -meter 1 Instrument zum mechanischen Ausmessen krummlinig begrenzter ebener Flächen
The Wordsmith Dictionary