From Proto-Baltic *irā (cf. Latvian ir, dialectal, archaic Latvian forms irād, iraid, irāg, which existed alongside *esti (cf. Old Church Slavonic єстъ (jestŭ), Russian есть (jest’), Lithuanian dialectal ẽsti, Old Prussian ast), initially with basically existential (“there is”) meaning, but later on extending to all copular meanings, thus replacing *esti. In Sudovian, also the first person form irm (“I am”) is derived from this stem. The origin of Proto-Baltic *irā is, however, unclear. Various sources have been proposed: an older interjection (cf. Lithuanian aurè (“look!”)), the particle and conjunction ir (“both... and...”), a noun with the meaning “existence,” “reality,” “thing,” or even (more recently) the Proto-Indo-European secondary third-person verbal ending *-r with a later -ā-extension.
- nėra (negative form)