I'm curious to ask if the suffix -tī for the infinitive in Balto-Slavic is related to the PIE third person, singular, present suffix -ti?

Although there is no reason (from a functional point of reasoning) to suppose such a relation, I recently learnt that the only "dialect" of Balto-Slavic that has undergone a transition to analyticity, namely Bulgaro-Macedonian, has lost both the infinitive and the ending -ti in 3rd p, sg verb conjugation, so morphologically there is some point in conjecturing some relation...

  • I found a discussion about the PIE infinitive, which is relevant to my questions, however, (unfortunately) no determinate answer was given there.. Commented May 30, 2016 at 11:59
  • I would guess that the B-S inf. -ti is the same -ti that forms abstract/action nouns in Greek (e.g. mē-ti-s "cunning"). Hard to see how a 3sg. suffix would change into an infinitive marker.
    – TKR
    Commented May 30, 2016 at 14:28
  • The B-Sl -ti is with a long i, while the PIS -is endings usually have evolved into short -i (OCS ), though. Commented May 30, 2016 at 15:20
  • Ah, good point.
    – TKR
    Commented May 30, 2016 at 16:32
  • The difference in length does mean, though, that there's even less reason to see this -tī as related to 3sg. -ti. In any case, I don't see how the fact that one Slavic dialect happens to have lost both these endings is any reason to think they're related. Looking at the page you linked to I see the -tī inf. is thought to derive from the dative of an action noun, which would make it cognate with the Greek type I mentioned above after all; the long i is simply due to the dative ending.
    – TKR
    Commented May 30, 2016 at 20:44

1 Answer 1


TL;DR: Infinitive suffix "-ти" and 3rd person singular present "-тъ" are essentially different.
They could reduce independently in Slavonic languages, but if they are both reduced, this seems to be just a coincidence.

In his "Slavonic Grammar with Correct Syntax" (1619), Meletius Smotrytsky marks 3rd person singular present suffix -тъ (pronounced with short [ɔ]).

So, the verb to read, "читати" [t͡ɕɨ-ta-ti] conjugates to "чтєтъ" [t͡ɕtɛ-tɔ].

Here's the scan of Smotrytsky's work

conjugation of the verb "to read"

Links: exact page, title page.

In modern Slavonic languages, indeed, these suffixed often reduce.

Ukrainian (my native language): the infinitive suffix remains the same, while the 3rd person singular present suffix reduces: "читати" [t͡ɕɨ-ta-tɨ] → "читає" [t͡ɕɨ-ta-ʲe] or even "чита" [t͡ɕɨ-ta] in Western dialects.

On the contrary, the modern Russian reduced suffix in the infinitive form while it retains 3rd person singular present suffix: "читать" [t͡ɕi-tatʲ] → "читает" [t͡ɕi-ta-ʲet].

So, as we can see, the distinction between Ukrainian and Russian suggests that both suffixes may retract independently.

  • 2
    I get your point, however, I don't think Smotrotsky grammar is a reliable source for proving the distinctiveness of the two suffixes. The root "чт-" < OCS чьт- and the the 1st p., sg suffix is -ou- (чт-оу), which is a late development of the nasal , prove it. Besides, if we suppose that the Slavic 3rd p. sg. suffix was -тъ < -tu and not the PIE -ti, then it coincides with the (Vedic) Sanskrit infinitive (-tum) - i.e. the ambiguity still stands... Commented May 30, 2016 at 12:34
  • By the way, Bytebuster (and the moderators), excuse me for the off-topic, but could you suggest some material explaining the phonetical development of Ukrainian from the Proto-Slavic stage to nowadays? Commented May 30, 2016 at 16:26
  • @LinguistNewbie - Do I understand well that your only reason to believe in a relationship is basically the appearance of the sound Ť at two places of the endings? It seems like too small amount of evidence to me to draw deeper conclusions. Incidentally, in Czech, the infinitive with -ti has been totally standard but became mostly archaic sometime in the 20th century. For example, to read was "čísti" but all young people today would say just "číst". On the other hand, he "čte". The singular 3rd person present verbs always end with a vowel and I think that they always have - in Czech. Commented May 30, 2016 at 17:55
  • 1
    As I said, another reason for supposing some relation between the two morphemes is that the descendants of the PIE suffix -ti: disappeared in both the infinitive and the 3rd p, sg suffix in Bulgaro-Macedonian, which is the earliest Slavic variety with written record. Regarding your other comment - all words in Proto-Slavic ended in a vowel (due to the "Law of rising vocality"), not only the verbs. Commented May 30, 2016 at 19:30
  • @LinguistNewbie, Frankly, I cannot recall off the top of my mind any English-based research on the topic of P.Sl → Ukr. phonetic transition. However, if you have a more specific question, please feel free to ask it here, and I strongly believe there are several prominent users to answer questions about the modern Ukrainian. Also. the Wikipedia article may be a good start. Commented May 30, 2016 at 23:44

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