LATIN DICTIONARYLexicon Latīnum
adjectivefirst/second-declension adjective

arithmēticus

arithmēticus (feminine arithmētica, neuter arithmēticum)
Classical[a.rɪtʰˈmeː.tɪ.kʊs]Ecclesiastical[a.ritˈmɛː.ti.kus]

Meaning

  1. adjectivearithmetical

Declension

singular
formmasculinefeminineneuter
nominativearithmēticusarithmēticaarithmēticum
genitivearithmēticīarithmēticaearithmēticī
dativearithmēticōarithmēticaearithmēticō
accusativearithmēticumarithmēticamarithmēticum
ablativearithmēticōarithmēticāarithmēticō
vocativearithmēticearithmēticaarithmēticum
plural
formmasculinefeminineneuter
nominativearithmēticīarithmēticaearithmētica
genitivearithmēticōrumarithmēticārumarithmēticōrum
dativearithmēticīsarithmēticīsarithmēticīs
accusativearithmēticōsarithmēticāsarithmētica
ablativearithmēticīsarithmēticīsarithmēticīs
vocativearithmēticīarithmēticaearithmētica

ărithmētĭcus, a, um, adj., = ἀριθμητικός,
I. of or pertaining to arithmetic, arithmetical: ratio, Vitr. 10, 16.—Subst.: ărithmētĭca, ōrum, n., arithmetic: in arithmeticis satis exercitatus, Cic. Att. 14, 12 fin.

Origins

From Ancient Greek ἀριθμητικός (arithmētikós, “arithmetical”), from ἀριθμός (arithmós, “number, counting”), from Proto-Indo-European *h₂ri-dʰh₁-mó-s, form of *h₂rey- (“to count, reason”).

Quick answers

What does arithmēticus mean in Latin?
arithmēticus, a adjective, means “arithmetical”.
How do you pronounce arithmēticus?
In classical Latin, [a.rɪtʰˈmeː.tɪ.kʊs]; in ecclesiastical (church) Latin, [a.ritˈmɛː.ti.kus].