-tsi

• -itsi

From Proto-Finnic *-cci. Cognate with Finnish -tse.

• IPA^(key): /ˈ-tsi/, [ˈ-tsʲi]
• Rhymes: -tsi
• Hyphenation: -tsi

-tsi

1. by, through, via; the suffix of the obsolete prolative case, indicating:
   1. route, path by which sth/sb travels.

      ‎meri (“sea”) + ‎-tsi → ‎meritsi (“by sea”)

      ‎jää (“ice”) + ‎-tsi → ‎jäitsi (“by ice”)

      ‎maa (“land”) + ‎-tsi → ‎maitsi (“by land”)

      ‎õhk (“air”) + ‎-tsi → ‎õhutsi (“by air”)

      Synonyms: mööda, kaudu, pidi

   2. means using which sth is done.

      ‎telefon (“phone”) + ‎-tsi → ‎telefonitsi (“by phone”)

      ‎meil (“email”) + ‎-tsi → ‎meilitsi (“by, via email”)

      ‎käsi (“hand”) + ‎-tsi → ‎käsitsi (“by hand, manually”) (this is probably the most common example of this suffix being used in everyday speech)

      ‎sõna (“word”) + ‎-tsi → ‎sõnutsi (“according to (the words of sb)”)

      Synonyms: (comitative case suffix) -ga, abil, teel

   3. way by which sth is done.

      ‎omavoli (“arbitrariness, maladministration”) + ‎-tsi → ‎omavolitsi (“arbitrarily”)

      ‎viha (“anger, rage”) + ‎-tsi → ‎vihatsi (“angrily”)

   4. position in which two or more people are standing (only from some body parts): X to X.

      ‎selg (“back”) + ‎-tsi → ‎selitsi (“back to back”)

      ‎külg (“side”) + ‎-tsi → ‎külitsi (“side by side”)

      ‎rind (“chest”) + ‎-tsi → ‎rinnutsi (“chest to chest, abreast”)

      ‎karv (“(body) hair”) + ‎-tsi → ‎karvutsi (“hair to hair”)

      ‎silm (“eye”) + ‎-tsi → ‎silmitsi (“eye to eye”) (this is also one of the most common examples of this suffix being used in everyday speech)

      ‎nägu (“face”) + ‎-tsi → ‎näotsi (“face to face”)

      Synonym: (only some of them, like "selg", "külg" and "rind") -kuti

Most grammars don't treat the prolative as a separate grammatical case, as it cannot be derived from just any nominal. The prolative suffix can only be appended to nouns, and usually occur only in set phrases, demonstrated in the usage examples above. Therefore, it is considered an adverbial suffix.

This suffix appends to the plural stem of the word.

As with many slang suffixes, there are probably multiple origins. The main origin is probably -tsa +‎ -i, but another influence would be loanwords ending in -si.

-tsi (slang)

1. Slang suffix, generally for nouns (with clipping).