-tis

From Proto-Italic *-tis, from Proto-Indo-European *-tis, suffix forming nouns from verbal roots.

• (Classical Latin) IPA^(key): [tɪs]
• (modern Italianate Ecclesiastical) IPA^(key): [tis]

-tis f (genitive -tis); third declension

1. (unproductive) suffixed to a verb stem to form a noun, usually denoting an action or result

• This suffix appears as part of some inherited nouns, but is not productively used to derive new nouns in Latin. Its function was taken over by other synonymous suffixes; in particular, the extended form -tiō f.
• Words formed with this suffix are generally feminine, but there are a few masculine exceptions such as fūstis m (“cudgel”), vectis m (“bar; lever, crowbar; bolt”).
• Many nouns that originally ended in *-tis lost the vowel *-i- in their nominative singular, making the ending into *-ts, which was simplified to Latin -s. For example, Proto-Indo-European *méntis (“thought”) became pre-Latin *ments, yielding historical Latin mēns (“mind”), oblique stem ment(i)- (as in genitive singular mentis, genitive plural mentium): the same root is found in the Latin verb meminī (“to remember, bear in mind”). Other similarly formed nouns include mors (“death”), oblique stem mort(i)-, from the root of morior (“to die”), and fors (“chance”), oblique stem fort(i)-. However, this loss of *-i- was prevented in certain nouns, e.g. vestis, restis, messis, tussis, probably to avoid creating awkward word-final clusters such as *-sts or *-sss.
• As usual in Latin, suffix-initial -t- was regularly replaced with -s- after a verb root ending in a dental plosive (-t- or -d-), and the resulting cluster was regularly assimilated to -ss-.
• Etymologically, this suffix inflected with i-stem endings, but as with other i-stem nouns, certain case endings were altered by analogy with consonant-stem nouns. Different nouns varied in the extent to which they adopted consonant-stem endings in the oblique cases: for example, tussis almost always uses the i-stem accusative singular tussim, whereas vestis uses the accusative singular vestem, and messis is attested in the accusative singular both as messim and (more often) as messem. (Based on quem and autem, Sihler supposes that -em as in mentem is actually the regular phonetic outcome of original *-im in Latin, and considers Latin accusative singular forms ending in -im to be analogical creations; Sihler suggests the adverb ending -tim developed phonetically from earlier -tīm.^[1])
• Based on old i-stem adverbial accusatives such as partim, the ending -tim gained an independent use as a productive suffix forming adverbs.

Third-declension noun (i-stem).

• (Classical Latin) IPA^(key): [tiːs]
• (modern Italianate Ecclesiastical) IPA^(key): [tis]

-tīs

1. masculine/feminine/neuter dative/ablative plural of -tus

• Vowles, Guy Richard (1928), “Studies in Greek Noun Formation”, in Classical Philology, volume 23, page 35
• Lindsay, W. M. (1894), The Latin Language, pages 340-342
• Allen, Joseph Henry; Greenough, James B. (1903), Allen and Greenough's New Latin grammar for schools and colleges: founded on comparative grammar, Boston: Ginn and Company, § 234