The headword is the present infinitive of the compound verb diopompe/omai. Lexicographers are the only extant source for forms of the un-compounded diopompe/omai, since the verb normally appears as a)podiopompe/omai (alpha 3297; LSJ entry at web address 1, Synagoge alpha828). For the general equivalence see Eustathius on Homer, Odyssey 10.481 a)/llws de\ koino/teron diopompei=n kai\ a)podiopompei=n e)fai/neto. The substantive diopomph/ can be found in Etymologicum Gudianum 147.54, with the gloss pe/myis, "mission"; cf. Clement of Alexandria, Stromata 7.6.33 th=i diopomph/sei tw=n kakw=n. For the meaning see Hesychius alpha6304 a)podiopompei=sqai: a)postre/fesqai, to\n a)potro/paion e)kpe/mpesqai makra/n, a)pokaqai/resqai, "to escort away: to turn away, to send the ill-omened one [sc. a scapegoat] far away, to purify"; delta1900 diopompei=sqai: kaqai/rein, i)di/ws de\ tou\s kaqai/rontas pro\s to\n prostro/paion *di/a a)pope/mpein, "to purify; properly, to send those who purify to [the shrine of] Zeus Prostropaios [= to whom one turns to obtain purification]". According to Etymologicum Magnum 125.33, which offers the etymology a)po\ tou= *dio\s kai\ tou= pompo/s, "from Zeus and escort", following a grammatical explanation of the verb (prw/ths suzugi/as diopompw=, diopomph/sw, "first conjugation"), the headword shmai/nei to\ a)potre/pesqai dia\ tou= a)potropai/ou *dio\s, a)potro/paios me\n *zeu\s, kai\ dai/mwn, a)potre/pwn ta\ a)/gh, "denotes the action of averting [evil] with the help of Zeus Apotropaios; [the epithet] apotropaios [for] Zeus and a demon means curse-lifting, turning away the pollution". Cf. Plato, Laws 854B i)/qi e)pi\ ta\s a)podiopomph/seis, i)/qi e)pi\ qew=n a)potropai/wn i(era\ i(ke/ths, "betake yourself to the purificatory rituals, betake yourself as a suppliant to the shrines of the evil-averting gods". For another instance of the verb in reference to purificatory rituals see Hesychius lambda691 s. v. *le/rnh qeatw=n (The Lerne of the theaters, Cratinus fr. 347 Kock = 392 K.-A.): "paroimi/a ti/s e)stin *argolikh\ *le/rnh kakw=n, h(\n a)podiopompou/menoi e)/legon. ta\ ga\r a)pokaqa/rmata ei)s tou=to to\ xwri/on e)ne/ballon, "there is a common saying, 'Argolian Lerne of ills' [= abyss of ills] which they used to say when they made purifications, for they used to send to that place all that they wanted to cleanse off" (cf. Strabo 8.6.8; Pausanias 8.15.8). For further relation to rituals of ka/qarsis see [Lysias] 6.53 th\n po/lin kaqai/resqai kai\ a)podiopompei=n kai\ farmako\n a)pope/mpein kai\ a)lith/rion a)palla/ttesqai, "purify the city, avert evil from there, expel the scapegoat and take away the sinner"; again Eustathius on Homer, Odyssey 10.481 pu=r zhtei= *)odusseu\s e)pi\ kaqa/rsei tou= dw/matos. e)do/koun ga\r oi( *(/ellhnes ou(/tw ta\ toiau=ta mu/sh kaqai/resqai diopompou/mena, "Odysseus is looking for fire, in order to purify the palace. It seems that in this way the Greeks used to clear off the uncleanness thrown away"; Plato, Laws 878A kaqh/rasqai kai\ a)podiopomph/sasqai to\n oi)=kon ... kata\ no/mon “purify and cleanse the house…according to rules”. See also Plato, Cratylus 396E au)/rion de/, a)\n kai\ u(mi=n sundokh=|, a)podiopomphso/meqa te au)th\n kai\ kaqarou/meqa e)ceuro/ntes o(/stis ta\ toiau=ta deino\s kaqai/rein, ei)=te tw=n i(ere/wn tis ei)=te tw=n sofistw=n; "tomorrow, if you too agree, we will conjure it away and purify ourselves, after having found some one either of the priest or of the sophist, skilled in doing such purifications"; scholion ad loc. (cf. n.1) a)podiopompei=sqai fasi\ a)potre/pesqai to\n prostro/paion *di/a kai\ oi(onei\ a)pokaqai/resqai ta\ deina\,"a. is explained as 'to turn to Zeus Prostropaios and so obtain effective purification from the evil". Eustathius on Homer, Odyssey 10.481, refers his interpretation of the word diopompei=sqai to the offerings of ram-fleeces as scapegoats to Zeus Meilichios, during the purificatory rituals which took place in the month Maimakterion (cf. delta 1210). The meaning escorting out [of the city] the sacred fleece seems to be the originary one; hence "conjure away" (Plutarch, Cato Maior 22 met' eu)prepei/as tou\s filoso/fous e)k th=s po/lews) or "chase away" a pollution (Cassius Dio 37.46.1 mi/asma, a damage (Iamblicus, On the Mysteries 1.13.21 bla/bhn, every kind of negative, ill-omened events or things (scholion on Pindar, Nemean 10 th\n e)/rin th\n pro\s tou\s krei/ttwnas; scholion [both the vetus and Tzetzes] on Aristophanes, Frogs 1340 tou\s xalepwta/tous tw=n o)nei/rwn; Clement of Alexandria, Stromata 7.6.33 kaka/.) both real or presumed (Ephorus in Plutarch, Lysander 17 [FGrH 70 F205] a)podiopompei=sqai pa=n to\ a)rgu/rion kai\ to\ xrusi/on w(/sper kh=ras, "remove all of the gold and silver as calamities". Libanius 15.1.34 opposes a)podiopompei=sqai to au(tw=| gene/sqai suneu/cesqai "wish to have happen to oneself".
[1] = Photius delta648; cf. Photius delta646, scholion on Plato, Cratylus 396E (where a)podiopomphso/meqa occurs) and to Hesychius delta1900.
[2] The present middle/passive imperative (third person) of the same verb, compounded with the prefix apo-. The expression, which seems a deprecatory formula, could refer to a person and consequently be translated "let us chase him away" in an unidentified quotation; see already at alpha 3297.