-sis

suffix

forming nouns of action or process

“basis, oasis, thesis, stasis”

OriginAncient Greek -σις →
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Meanings

suffix

plural -ses

  1. forming nouns of action or process

    catharsis, dialysis, diagnosis, crisis

  2. medicineforming nouns of condition

    psoriasis, sepsis, tuberculosis, psychosis

  3. forming additional nouns

    basis, oasis, thesis, stasis

Origin

  1. Ancient Greek-σις“forms noun of action”
  2. English-sis

Ultimately from Ancient Greek -σις (-sis, “forms noun of action”), often via Latin or French. Identical in meaning with Latin -entia, English -ing.

More words from Ancient Greek

Full word history & related roots →
Cite this entry
APA

-sis. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/-sis

MLA

“-sis.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/-sis. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “-sis,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/-sis.

Source: -sis on Wiktionary, CC BY-SA 4.0.