An Etymological Dictionary of Astronomy and Astrophysics

Generally,a device for indicating a number or amount.
Any of various instruments for detecting ionizing radiation and for registering counts. → Geiger counter.

Etymology (EN): M.E. countour, from O.Fr. conteor, from L. computator, from computa(re) “to compute” + → -tor suffix forming personal agent nouns mainly from verbs.

Etymology (PE): Šomârgar, from šomâr present tense stem of šomârdan “to count,” → count

• agent suffix -gar.