Reconstruction:Proto-Slavic/-tъ

From Proto-Balto-Slavic *-tas; the suffix continues both Proto-Indo-European *-tós and *-tus. A distinguishing feature between the two is that lemmas formed with the u-stem suffix, later were extended with *-kъ, e.g. Serbo-Croatian podátak (“datum”) < *datъ (“load, something given”).

For the participle use, compare Proto-Germanic *-þaz and Latin -tus. However the verb classes that take *-þaz in Proto-Germanic (so-called "weak verbs"), take *-nъ in Proto-Slavic, which is cognate with Proto-Germanic *-naz which in turn usually forms participles of verbs that take *-tъ in Proto-Slavic.

*-tъ m

1. Deverbal from perfective mono-syllabic simple stems, forms passive participles

   Synonym: *-nъ

   From ū-grade root:

   *obutъ (“footwear put on”) ← *obuti (“to put on footwear”)

   *nadutъ (“swelled”) (+ *na-) ← *duti (“to blow up”)

   From ī-grade root:

   *šitъ (“sewn”) ← *šiti (“to sew”)

   *bitъ (“beaten”) ← *biti (“to beat”)

   From nasal-grade root:

   *klętъ (“pitiable, damned”) ← *klęti (“to curse”)

   *vъzętъ (“taken”) ← *vъzęti (“to take, to acquire”)

2. Deverbal, forms nouns (usually with o-grade)

   *potъ (“sweat”) ← *peťi (“to bake”)

   *letъ (“flight”) ← Pre-Slavic *lekti (“to spring, to hop”)

   *moltъ (“hammer”) ← *melti (“to mold”)

   *datъkъ (“levy”) ← **datъ ← *dati (“to give”)

   *vitъkъ (“coil”) ← **vitъ ← *viti (“to wind, to curve”)

   *ostatъkъ (“remainder”) ← **ostatъ ← *ostati (“to remain”)

• *-kъ
• *-slo
• *-atъ, *-itъ, *-ьnъ