From Proto-Balto-Slavic *bū́ˀtei. Cognates include Latvian būt and Lithuanian būti.
The present tense forms are derived from Proto-Indo-European *h₁ésti (“to be”).
byut
| infinitive | byut | ||
|---|---|---|---|
| supine | byutu | ||
| verbal noun | byušona | ||
| indicative | |||
| past | present | future | |
| 1st singular | beju | asmu, asu | byušu |
| 2nd singular | beji | esi | byusi |
| 3rd singular | beja | ir, irā | byus |
| 1st plural | bejom | asam | byusim |
| 2nd plural | bejot | asat | byusit |
| 3rd plural | beja | ir, irā | byus |
| subjunctive | imperative | ||
| 1st singular | byutum | singular | esi |
| 2nd singular | byutim | plural | esit, ejit |
| 3rd singular | byutu | ||
| 1st plural | byutumem | debitive | juobyut |
| 2nd plural | byutumet | converb | byudams |
| 3rd plural | byutu | ||
| participles | |||
| past | present | future | |
| active | bejs | asūšs | — |
| passive | byuts | asams (asam) |
— |
| oblique | bejs | ass (asūt) |
byuškis (byušūt) |
| infinitive | nabyut | ||
|---|---|---|---|
| supine | nabyutu | ||
| verbal noun | nabyušona | ||
| indicative | |||
| past | present | future | |
| 1st singular | nabeju | naasmu, naasu | nabyušu |
| 2nd singular | nabeji | naesi | nabyusi |
| 3rd singular | nabeja | nav, navā | nabyus |
| 1st plural | nabejom | naasam | nabyusim |
| 2nd plural | nabejot | naasat | nabyusit |
| 3rd plural | nabeja | nav, navā | nabyus |
| subjunctive | imperative | ||
| 1st singular | nabyutum | singular | naesi |
| 2nd singular | nabyutim | plural | naesit, naejit |
| 3rd singular | nabyutu | ||
| 1st plural | nabyutumem | debitive | najuobyut |
| 2nd plural | nabyutumet | converb | nabyudams |
| 3rd plural | nabyutu | ||
| participles | |||
| past | present | future | |
| active | nabejs | naasūšs | — |
| passive | nabyuts | naasams (naasam) |
— |
| oblique | nabejs | naass (naasūt) |
nabyuškys (nabyušūt) |