The Balto-Slavic root *leup- ‘to peel’ (Lith. lùpti, lùpa, Sl. *lupti) can be derived from the root *lep- ‘id.’ (Gk. λέπω) by assuming an original paradigm pres. *lep-e/o- : aor.-inf. *p-. The aorist-infinitive stem developed as follows: *p- > *ulp- → *lup- (after pres. *lep-) → new full grade *leup-.
