*p(o)rk^u̯-éi̯e/o-

If we equate Pal. parkui-^(di) with CLuw. parkuwaima/i-, we can reconstruct tentatively a causative-iterative in *-éi̯e/o- with either an o-grade or zero-grade of the root (cf. Melchert 1994a:214 on the Palaic outcome of *r̥). However, this is not assured synchronically neither for Palaic, which could be interpreted as a verb in *-i̯e/o- instead, PAnat. *pérk^u̯-i̯e/o-, nor for Luwian, which could be interpreted instead as a verb in -ā(i)-^(di) (< *-éh₂-i̯e/o-). More attestations are required to be absolutely certain. Regarding the Hittite data, Kloekhorst (EDHIL:638f.) reconstructs convincingly a deradical verb in *-i̯e/o- for Hitt. parku(y)e/a-^(mi) ‘to purify’, after pleading for a root of the shape parkw- (< *pErk^u̯-), which is supported by its Anatolian cognates. The reduplicated Luwian cognate papparkuwa-^(ti) assures us that the initial consonant of the root is voiceless, because the analogical pattern in Luwian will change the consonant of the non-reduplicated part from fortis to lenis (i.e. CV-CCV- → CV-CV-) and not the other way around. Thus, a root verb can be reconstructed with certainty, i.e. *pErk^u̯-i̯e/o-. Contra Melchert 1994a:191 et passim, who accepts the reconstruction of a root *berĝ-u̯- under the old assumption that the labial glide was not part of the root. For a survey of the literature including various Indo-European etymologies see HEG P:478f.

[D.S.]

Kloekhorst (EDHIL:638f.) proposes to connect PAnat. *perk^u̯- ‘to purify’ with OHG furben ‘to clean’, which semantically makes good sense. In EWAhd III:654f., OHG furben ‘to clean’ is derived from the root PIE *prep- ‘to draw attention, appear’ (LIV²:492; cf. Gk. πρέπω ‘to draw attention, excel’), which is semantically problematic, though.Cf. EWAhd III:654f. as well as, e.g., LIV²:492: “ganz unsicher” and EDG:1231: “quite uncertain”.Thus, Kloekhorst’s etymological suggestion of PAnat. *perk^u̯- ‘to purify’ equating OHG furban ‘to clean’ is preferable.

The only cognates of the PAnat. root *perk^u̯- ‘to purify’ might be PGerm. *furƀi̯an- (cf. OHG furben ‘to clean’ and OS furvian* ‘to polish, purify’), which may go back to PIE *pr̥k^u̯‑i̯é/ó- ‘to clean’.Differently, this verb can also go back to PIE *pr̥k^u̯‑éi̯e/o- which, on the one hand, could match Pal. parkui‑^(di) and CLuw. parkuwaima/i- phonologically (cf. above), but is, on the other hand, morphologically not verifiable.Phonologically, this connection is possible: (early) PGerm. *furf‑i̯án- (*χ^u̯ > *f after *f‑)Cf. PGerm. *femf(e) < PIE *penk^u̯e ‘5’ (EWAhd III:240f.) for the same assimilation process in a very similar environment (*‑k^u̯- > PGerm. ‑f‑/fVR_). For a different formulation of the sound law (pre‑PGerm. *k^u̯ > *p after resonant and anlauting labial), cf. EDPG:140.> PGerm. *furƀ‑i̯án- (Verner’s Law) > OHG furb‑en, OS furv‑ian*. Kümmel (in LIV²⁺ s.v. ?*perk^w‑) objects that one would rather expect delabialization of PGerm. *g^u̯ (< *k^u̯_´) before *i̯, but, according to Ringe 2006a:112, “this point of PGmc historical phonology must remain uncertain.”The relative chronology of the relevant sound changes is still a matter of debate. In the present case, the most important example is ON ylgr ‘she‑wolf’, which, however, may also be explained by later, viz. inner‑Norse sound laws, cf. Ringe 2006a:111f. with refs. and, on a different view, EDPG:598.The exact Anatolian equivalent is attested as Hitt. parkuu̯a(i)- ‘to purify’ (cf. EDHIL:638f.). The remaining Anatolian verbal cognates, however, may continue different stem formations, cf. above. Therefore, only the Hittite-Germanic isogloss is reconstructable for PIE as PIE *pr̥k^u̯‑i̯é/ó- ‘to clean’.

OHG furben ‘to clean’, OS (gl.) furvian* ‘to polish, purify’
EWAhd III:654f., Tiefenbach 2010a:114