Etymology 1
Proto-Indo-European *-tós Latin -tus
From Proto-Italic *-tos, from Proto-Indo-European *-tós (suffix creating verbal adjectives).
Compare Proto-Slavic *-tъ, Proto-Germanic *-daz, *-taz.
Suffix
-tus (feminine -ta, neuter -tum); first/second-declension suffix
- Forms the past participle of verbs.
- Forms adjectives having the sense "provided with".
- iūs (“law, legality; equity, the right, justice”) → iūstus (“lawful, legal; equitable, rightful, just”)
- onus (“a burden or load, especially one excessive in magnitude”) → onustus (“burdened”, “heavily laden”, “overencumbered by a load”)
Usage notes
Verb stems may be modified by the attachment of this suffix in certain predictable or unpredictable ways:
- Stem-final b and g are regularly devoiced to p and c respectively. If the stem ends in a short vowel directly followed by g, this vowel is usually lengthened (due to Lachmann's Law) but sometimes remains short (especially after the high vowel i, as in cōnstrictus from cōnstringō or fictus from fingō).
- agō (“lead”) + -tus → āctus
- scrībō (“write”) + -tus → scrīptus
- Stem-final qu is delabialised, giving c. Likewise, stem-final ngu is delabialized to nc.
- coquō (“cook”) + -tus → coctus
- exstinguō (“extinguish”) + -tus → exstīnctus
- Stem-final v either merges with the preceding vowel (yielding the diphthong au in the case of -av-, or the long vowels ō and ū in the case of -ov- and -uv-/-u-) or is replaced with c. These are the expected outcomes of the distinct Proto-Italic consonants *w and *gʷ, respectively, which merged between vowels in Latin as -v-. However, Latin c in this context does not always descend from original Proto-Italic *gʷ, because analogical changes took place after the merger and affected the distribution of c.
- caveō (“beware”) + -tus → cautus
- voveō (“vow”) + -tus → vōtus
- iuvō (“aid”) + -tus → iūtus
- vīvō (“live”) + -tus → vīctus
- solvō (“untie,set free,separate”) + -tus → solūtus
- Stem-final d or t fuses with the t of the suffix, giving -ssus. This is simplified to -sus if not preceded by a short vowel. Similarly to g-final stems, d-final stems sometimes (but not always) have lengthened vowels in the past participle due to Lachmann's Law.
- cadō (“fall”) + -tus → cāsus
- Stem-final rg also fuses with the t, giving -rsus.
- mergō (“plunge”) + -tus → mersus
- tergeō (“rub, cleanse”) + -tus → tersus
- Stem final ll or rr sometimes fuses with the t, to -lsus and -rsus respectively.
- currō (“run”) + -tus → cursus
- When attached to stems of 1st, 2nd or 4th conjugation verbs, the long vowel at the end of the present stem may be either retained unchanged, replaced by short -i-, or dropped entirely. It's retained for most 1st conjugation verbs, while it becomes short i for many 2nd conjugation verbs:
- errō (errā-) (“wander”) + -tus → errātus , audiō (audī-) (“hear”) + -tus → audītus
- moneō (monē-) (“advise,remind”) + -tus → monitus
- augeō (augē-) (“increase”) + -tus → auctus
Noun stems generally do not exhibit these modifications; there are some adjectives ending in -stus that originate from s-stem nouns, such as onustus, scelestus, but overall the suffix is rarely found attached directly to a consonant-final noun stem. Most derivatives in -tus from nouns include a long vowel before the -t-, which may in some cases originate partly or wholly from the final vowel of the stem (for example, barbātus from barba and aurītus from auris[1]), but which at least eventually was subject to reanalysis as part of the suffix; see -ātus, -ītus, -ūtus.
Etymology 2
From Proto-Italic *-tus, from Proto-Indo-European *-tus (suffix deriving action nouns from verb roots).
Cognate with Sanskrit -तुम् (-tum), Proto-Germanic *-þuz, Ancient Greek -τύς (-tús), Proto-Slavic *-tъ.
Suffix
-tus m (genitive -tūs); fourth declension
- Forms action nouns from verbs.
- cadō + -tus → cāsus
- habeō (“I have, possess, have on, carry, wear”) + -tus → habitus (“a state or condition of being, physical character, demeanour, style of dress”)
- sūmō (“I spend [time, effort, money, etc.]”) + -tus → sūmptus (“expenditure”)
Usage notes
The verb stem undergoes the same modifications as for the participle suffix; see -sus.
Etymology 3
From Proto-Indo-European *-tuHts (abstract-noun forming suffix). Compare Proto-Celtic *-tūss, Gothic -𐌳𐌿𐌸𐍃 (-dūþs). See -tās.
Suffix
-tūs f (genitive -tūtis); third declension
- Forms collective/abstract nouns from adjectives or other nouns.
- iuvenis (“young, a young man”) → iuventūs (“the young, young men collectively; the period or qualities of youthful manhood, youth”)
- senex (“an old man”) → senectūs (“old men collectively; the period or condition of old age”)
Usage notes
Same as for the participle suffix.
Etymology 4
From Proto-Italic *-tos. Compare Ancient Greek -τός (-tós), found in the adverb ἐντός (entós, “within”), and Sanskrit -तस् (-tas), found as an ablatival ending in अतस् (átas), अग्रतस् (agratás).[2]
References
Pike, Moss (2011) Latin -tās and Related Forms. Ph.D. dissertation, University of California, Los Angeles. Page 37 Rosén, H. (2007). "A Latin adverbialization: -(i)tus from separative-locative to manner adverb." Historische Sprachforschung / Historical Linguistics, 120, 215–230. http://www.jstor.org/stable/40849301
