From Proto-Baltic *-ība, perhaps from Proto-Indo-European *bʰh₂-o-, from a stem *bʰeh₂- (“to shine”), first applied to i-stems, from which it incorporated the stem-final i, and then spread to other stem classes. Cognates include Lithuanian -yba (cf. tikýba (“belief, faith”)), Common Slavic *-ьba (Old Church Slavonic -ьба (-ĭba), Russian -ба (-ba)).
- Added to adjectives (sometimes to nouns) to form abstract nouns, especially those referring to the state or property that corresponds to the original adjective (like, e.g., Eng. -ity).