LATIN DICTIONARYLexicon Latīnum
adjectivefirst/second-declension adjective

achāicus

achāicus (feminine achāica, neuter achāicum)
Classical[aˈkʰaː.ɪ.kʊs]Ecclesiastical[aˈkaː.i.kus]

Meaning

  1. adjectiveof or pertaining to Achaea (A region in southern Greece)

Choosing the right word Döderlein's Latin Synonyms

Achivi · Achæi · Achaius · Achaicus · Troius · Troicus

1. Achivi are the Homeric Greeks, or Ἀχαῖοι; Achæi are either the inhabitants of Achaia, or, in the poets, the Greeks at large, as contemporaries of the Romans. Cic. Divin. i. 16. Cum Achivi cœpissent inter se strepere. Compare this with Cæcil. 20. Quod cum sibi Achæi patronum adoptarant. 2. Achaius is the adj. of Achivus. Hor. Od. i. 15. 37. Virg. Æn. ii. 462; but Achaicus is the adj. of Achæus. Cic. Att. i. 13. 3. Troius is the more select term, as adj. of the old heroic and Homeric Troja; Troicus, the usual adj. of the country Troas, without reference to the Trojan war. (v. 306.)

Declension

singular
formmasculinefeminineneuter
nominativeachāicusachāicaachāicum
genitiveachāicīachāicaeachāicī
dativeachāicōachāicaeachāicō
accusativeachāicumachāicamachāicum
ablativeachāicōachāicāachāicō
vocativeachāiceachāicaachāicum
plural
formmasculinefeminineneuter
nominativeachāicīachāicaeachāica
genitiveachāicōrumachāicārumachāicōrum
dativeachāicīsachāicīsachāicīs
accusativeachāicōsachāicāsachāica
ablativeachāicīsachāicīsachāicīs
vocativeachāicīachāicaeachāica

Charlton Lewis's shorter dictionary for students: the same scholarship in plain, modern definitions.

Achāicus adj.,
Achaean, Grecian: manus, V.: ignis, H.: homines.

Origins

Derived from Ancient Greek Ἀχᾱΐᾱ (Akhāḯā) + -icus (“of”, “pertaining to”, adjective-forming suffix)

Quick answers

What does achāicus mean in Latin?
achāicus, a adjective, means “of or pertaining to Achaea (A region in southern Greece)”.
How do you pronounce achāicus?
In classical Latin, [aˈkʰaː.ɪ.kʊs]; in ecclesiastical (church) Latin, [aˈkaː.i.kus].