Reconstruction:Proto-Balto-Slavic/lēiˀstei

• *lēiˀstéi
• *léiˀstei[1] (Rasmussen)

• *laiˀstéi

Exact origin disputed, but perhaps ultimately from Proto-Indo-European *(s)leh₁- (“to release”) ~ *(s)ley- (“to slide, to slip”) whence Hittite [script needed] (lāⁱ-, “to release”):

• Derksen (EDBIL): From Proto-Indo-European *leyd- (“to play, contend”), related to Old Irish láidid (“to exhort”), Latin lūdō (“to play”).
• Rasmussen, Klingenschmitt: From Proto-Indo-European *leh₁id-, related to Proto-Germanic *lētaną (“to let”), perhaps Old Church Slavonic лѣть (lětĭ, “permissibly”), лѣтьба (lětĭba, “possibility”), Ancient Greek λαιδρός (laidrós, “bold, impudent”) (via alternative extensions).
• Smoczyński: Rebracketed from a dʰé-present of Proto-Indo-European *leyH-, whence Proto-Balto-Slavic *leiˀtéi (“to pour”).

Long grade per Stang (affirmed by Bammesberger), eventually shortened due to lenition of V̄R-diphthongs. Oxytone due to Latvian broken tone, hence no application of Hirt's law.[2]

Rasmussen proposes short grade (due to pre-Balto-Slavic laryngeal metathesis) and stress on the root.

*lēiˀstei

1. to let, to allow
2. to release, to set in motion

   (in modern descendants) → to publish, to launch

Varying:

• athematic present in Old Lithuanian
• je-present in modern descendants

Fixed accent for later je-present conjugation. Possibly mobile accent for earlier athematic conjugation.

• *láiˀdas (resultant nominal)
  • East Baltic:
    • ⇒ Latvian: palaidējs m, palaidēja f (“launcher”)
    • ⇒ Lithuanian: paláidas (“lax, slack”)
    • ⇒ Lithuanian: nuolaidùs (“pliable”)
    • ⇒ Lithuanian: láidoti (“to burry”)
  • West Baltic:
    • ⇒ Old Prussian: palayde (per Cīzemers: "Nachlass eines Verstorbenen")

• *leiˀtéi (“to pour”) (possibly)
• *līˀd-
  • ⇒ Lithuanian: lýsti (“to give away”), lydė́ti (“to escort”)

With е̄-vocalism:

• East Baltic:
  • Lithuanian: léisti (standard)

With a-vocalism:

• East Baltic:
  • Latvian: laîst
  • Lithuanian: láisti (dialectal, Fraenkel)

• “leisti”, in Lietuvių kalbos etimologinio žodyno duomenų bazė [Lithuanian etymological dictionary database], 2007–2012
• Derksen, Rick (2015) “leisti”, in Etymological Dictionary of the Baltic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 13), Leiden, Boston: Brill, →ISBN, page 277