The etymology proposed by Apion, an Alexandrian grammarian of the 1^st century CE, probably derives from his lost Aegyptiaca (cf. Müller 1841, 509, fr. 4; Dillery 2003, 389) and is preserved only through Josephus’ polemical account (Contr. Ap. II.20–27). Apion derives σάββατον ("Sabbath") from an allegedly Egyptian term for groin pain (σαββάτωσις in Josephus’ report in II.21, σαββώ in his refutation in II.27). According to Josephus’ presentation, Apion claimed that 110,000 Jews were expelled from Egypt and that groin swellings developed among them (βουβῶνας ἔσχον, II.21, 56,30 Niese) after six days of travel. Having reached Judaea, they consequently rested on the seventh day and named it σάββατον, supposedly preserving the Egyptian language (σώζοντες τὴν Αἰγυπτίων γλῶτταν, II.21, 56,32 Niese). As Feldman (1988, 224 n. 62) points out, Apion’s explanation also associates Sabbath observance with the Exodus, one of its commemorative functions in Jewish tradition (Deut. 5:15). A comparable aetiological account in Justin’s Epitoma Historiarum Philippicarum Pompei Trogi XXXVI.2.14 associates the institution of the Sabbath with the end of the Jews’ hunger during the Exodus (cf. Feldman 1993, 163–6; Gruen 1998a, 48; 1998b, 98).

The putative etymology combines a cross-linguistic derivation based on formal resemblance with an aetiological narrative (αἰτία, Contr. Ap. II.20, 56,28; II.21, 56,30 Niese). The name of the Sabbath is traced to an allegedly Egyptian designation for the affliction that compelled the Jews to rest. In Niese’s text (1889, 56,26–57,24), σαββάτωσις resembles σάββατον principally through the shared sequence σαββατ-, while its ending -ωσις belongs to a class of Greek nominal formations in -σις, particularly productive in technical and scientific vocabulary (cf. Schwyzer 1939, 505–6; van Emde Boas et al. 2019, 267, §23.27). The ending -ωσις is also familiar from formations denoting pathological conditions (cf. Debrunner 1917, 103, §207; Scheller 1955, 298). The narrative of illness and rest supplies the explanation, but Josephus’ report specifies no phonological or morphological rules governing the derivation. 

Josephus introduces Apion’s etymology with ironic praise (θαυμαστήν τινα καὶ πιθανὴν ... αἰτίαν, II.20, 56,27–8 Niese; cf. Jones 2005, 290 n. 46), before dismissing it as nonsense (φλυαρία, II.22, 57,1 Niese) and condemning its shamelessness (ἀναίδεια, II.22, 57,2; II.26, 57,20 Niese) and ignorance (ἀμαθία, II.26, 57,20 Niese). Josephus first challenges the historical narrative by exposing what he regards as its internal inconsistencies, a characteristic feature of his polemical method (cf. Cohen 1988, 4): he considers it implausible that all 110,000 Jews should have been afflicted simultaneously, although Apion’s surviving account does not explicitly state that all were afflicted (cf. Barclay 1998, 214). Josephus further objects that Apion portrays the Jews as blind, lame and diseased, yet capable of traversing the desert and defeating armed opponents (II.22–24; cf. Feldman 1988, 224). Their supposed arrival in Judaea after six days also contradicts Apion’s account of Moses spending forty days on Mount Sinai (II.25–26). 

Finally, Josephus rejects the etymology as a “grammatical transposition” (γραμματικὴ μετάθεσις, II.26, 57,20 Niese), arguing that σαββώ and σάββατον are very different: τὸ γὰρ σαββὼ καὶ σάββατον πλεῖστον ἀλλήλων διαφέρει (‘For σαββώ and σάββατον differ considerably from one another’, II.27, 57,21 Niese). He explains that σάββατον means “rest from all work” (ἀνάπαυσις ἀπὸ παντὸς ἔργου) in the language of the Jews (see also Josephus, Antiquitates Judaicae I.33; cf. Weiss 1998, 374 n. 29), whereas σαββώ allegedly denotes “groin pain” in Egyptian, according to Apion himself (καθάπερ ἐκεῖνός φησι, II.27, 57,23 Niese). While μετάθεσις can denote the substitution of letters or sounds (cf., e.g., Apollonius Dyscolus, De adverbiis 144,19, 189,5 Schneider), Josephus does not specify the linguistic alteration involved. Dillery (2003, 387–8) and Jones (2005, 289–90) interpret Josephus’ rejection of the etymology as part of a broader attack on Apion’s scholarly competence, particularly his authority as a grammarian (for Apion’s unconventional etymologies of Homeric vocabulary, cf. Dillery 2003, 389). Dillery (2003, 388) also suggests that Josephus’ later account of Apion’s death following a failed therapeutic circumcision (Contr. Ap. II.143) may constitute an ironic response to Apion’s explanation of the name σάββατον in terms of groin pain.

A textual difficulty arises in II.21, where manuscript L reads σαββάτωσις, printed by Niese (1889, 57,1), whereas Josephus’ subsequent refutation in II.27 contrasts σαββώ with σάββατον. Since σαββάτωσις resembles σάββατον more closely than σαββώ does, Josephus appears to criticise a different expression from the one introduced in his report. Arlenius’ editio princeps (1544, 940,8), Müller (1841, 509, fr.4,10), Dindorf (1847, 369,3–4) and Naber (1896, 244,19) instead print the accusative σαββάτωσιν in II.21. The accusative is syntactically expected after καλοῦσιν (Smyth 1920, 362, §1613; van Emde Boas et al. 2019, 363–4, §30.10), whereas the nominative might reflect citation of the alleged Egyptian term in its lexical form (cf. Smyth 1920, 261, §940). Whether σαββάτωσιν reflects an independent manuscript reading or an editorial grammatical adjustment remains uncertain.

These earlier editions preserve the discrepancy between II.21 and II.27, printing σαββάτωσιν or σαββάτωσις in II.21 but σαββώ in II.27 (Arlenius 1544, 940,22–3; Dindorf 1847, 369,27, 30; Naber 1896, 245,12,15). Müller (1841, 509, fr. 4) reproduces only the former passage among his Aegyptiaca fragments. Thackeray (1926, 300,10) and Reinach (1930, 62,20) instead print σαββώ in II.21, bringing Josephus’ report into lexical agreement with his refutation in II.27. Reinach (1895, 128 n. 1; 1900, 14–15; 1930, 62, apparatus) explicitly identifies this reading as his own emendation, supported by the ancient Latin translation: Boysen (1898, 77,12 and apparatus) records sabbo in manuscripts B, C and V, whereas P reads sabbato, also printed by Boysen but regarded by Reinach as a secondary corruption that helps explain the emergence of Greek σαββάτωσις. The Latin sabbo readings offer possible support for Reinach’s conjecture, although they may also reflect harmonisation with II.27, the passage that itself motivates the emendation. Barclay (1998, 207 n. 27) endorsed Reinach’s emendation, suggesting that σαββάτωσις and Latin sabbato might be secondary alterations intended to make Apion’s etymology more plausible.

Two further textual variants are noteworthy. In II.21, Arlenius (1544, 940,8) prints τὸ δὲ βουβῶνος ἄλγος, whereas Müller (1841, 509, fr. 4,9–10), Dindorf (1847, 369,3), Niese (1889, 57,1) and Reinach (1930, 62,19) print τὸ γὰρ βουβῶνος ἄλγος. The latter makes the alleged Egyptian designation explicitly explanatory of the preceding account. In II.26, Arlenius (1544, 940,21), Dindorf (1847, 369,25–6), Niese (1889, 57,20) and Naber (1896, 245,11) print γραμματικὴ μετάθεσις ἀναίδειαν ἔχει, without ἢ after μετάθεσις. Niese proposes inserting ἢ in his apparatus, and Reinach (1930, 63,13) adopts the conjecture in his text. This affects the syntactic construction of Josephus’ accusation but not the linguistic objection.

This discrepancy admits different explanations. More generally, Jones (2005, 303–8) argues that Josephus selectively arranged and sometimes distorted material from Apion’s lost Aegyptiaca, raising questions about the completeness and reliability of his presentation. Revising his earlier endorsement of Reinach’s emendation, Barclay (2007, 179 n. 71) suggests that Josephus may have abbreviated a more elaborate argument. On this reconstruction, Apion first identified σαββώ as an Egyptian word for the groin or penis and then formed or invoked σαββάτωσις as a designation for its inflammation, using an ending resembling those of Greek medical terms. The latter expression supposedly furnished the basis for σάββατον. Josephus would thus have omitted an intermediate step and directed his criticism at the alleged Egyptian anatomical term. On this account, the Latin sabbo readings may themselves reflect scribal harmonisation with II.26–27 rather than preserve the original wording of II.21. Since the proposed intermediate step is not explicitly attested, however, Barclay’s reconstruction remains conjectural.

Scheller (1955), by contrast, interprets Apion’s etymology as involving the formation of σαββάτωσις from σάββατον, rather than the reverse. He regards σαββάτωσις as a jocular Greek formation with the ending -ωσις, also found in medical terminology, suggesting a ‘Sabbath disease’. On his reconstruction, the expression referred to a groin ailment that supposedly necessitated sexual abstinence, conceived as a form of Sabbath rest. He further regards σαββώ as a familiar shortened form of σαββάτωσις and suggests that Josephus deliberately employed this less recognisably related form in his refutation to emphasise its difference from σάββατον. Scheller thus understands the explanation attributed to Apion as an Alexandrian joke rather than a genuine derivation from Egyptian. His reconstruction remains conjectural, particularly regarding the sexual connotations and Josephus’ intentions. Gruen (2004, 45–6; 2016, 259) likewise considers the possibility that Apion’s etymology was intended as a sardonic joke rather than a malicious attack on Jewish customs.

The textual evidence thus leaves open whether the discrepancy between σαββάτωσις in II.21 and σαββώ in II.27 reflects textual corruption, an abbreviated account of Apion’s derivation, or Josephus’ differentiation of the two forms in his report and refutation. Reinach’s emendation eliminates the discrepancy by reading σαββώ in both passages, whereas the interpretations proposed by Scheller (1955) and Barclay (2007, 179 n. 71) allow both forms to be retained. Since Apion’s original formulation is lost, it remains uncertain whether he derived σάββατον directly from the alleged Egyptian σαββώ, through an intermediate σαββάτωσις, or whether σαββάτωσις was itself a jocular formation from σάββατον.