1. Root

 2.per, 2.sper

2. Lexical meanings

 DE: fliegen

3. Comparative evidence

4. Formally comparable roots

 1.per, 1.spelh₁, 1.spelh₂, 1.spelh₃, 1.spend, 1.sper, 1.prend, 1.sprend, 2.spelh₁, 2.spelh₂, 2.spelh₃, 2.spend, 2.prend, 2.sprend, 3.per, 3.sper, perd, perh₂, perh₃, perk, pert, perḱ, prek, prekʷ, preḱ, preh₁, prei̯h₁, prei̯h₂, prei̯h₃, prep, pres, pret, preu̯, preu̯s, preu̯th₂, preḱ, sep, speh₂, spelt, spenh₁, sperdʰ, perǵʰ, sperǵʰ, speu̯d, speḱ, splend, spreg, prengʰ, sprengʰ, spi̯eu̯h₁, spi̯eu̯h₂, spi̯eu̯h₃, spti̯eu̯h₂, spti̯eu̯h₃

5. Formally/Semantically comparable roots

6. Revised root variants

7. Comments

8. References

LIV = Rix, Helmut et al. 2001. Lexikon der indogermanischen Verben: Die Wurzeln und ihre Primärstammbildungen. 2 Aufl. Wiesbaden: Dr. Ludwig Reichert Verlag.