castus

• (Classical Latin) IPA^(key): [ˈkas.tʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈkas.t̪us]

Verbal adjective from the same root of careō (“I lack”),^[1] perhaps from Proto-Indo-European *ḱes- (“to cut”). Compare the meanings of pūrus/putus and derived putō. Related to Etruscan 𐌂𐌀𐌔𐌕𐌂𐌄 (castce).

castus (feminine casta, neuter castum, comparative castior, superlative castissimus, adverb castē); first/second-declension adjective

2. morally pure, guiltless, spotless

   Synonyms: innoxius, īnsōns, innocēns

   Antonyms: reus, obnoxius, noxius, cōnscius

3. especially in regard to sexual morality: pure, chaste, unpolluted, virtuous, continent
   • 8 CE, Ovid, Fasti 4.307–308:

     casta quidem, sed nōn et crēdita: rūmor inīquus
     laeserat, et falsī crīminis ācta rea est.

     Chaste, [she was] indeed, and yet had not been believed [to be so]:
     unjust slander had wronged her, and she was charged on a false accusation.
     (See Claudia Quinta.)

4. pure, free from barbarisms
5. in a religious context: religious, pious, holy, sacred

First/second-declension adjective.

• castificō
• castīgō
• castitās
• Castī connūbiī (of chaste wedlock)
• incestus

From careō +‎ -tus, thus from the same root as Etymology 1.

castus m (genitive castūs); fourth declension

2. (pre-Classical, post-Classical) an abstinence from sensual enjoyments on religious grounds

   Synonym: castimōnia

Fourth-declension noun.

• incestus

• “castus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “castus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• "castus", in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• castus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.