Areal reconstruction

*sVwsVw- - horse (SED No. 199)

The Sem. terms listed below are commonly thought to be borrowed from an IE satəm-language, v. Gamkrelidze-Ivanov 1984 560, 914 (PIE *ek[h]wo- ‘horse’) and Tropper 2000 45 (with a special emphasis on Luvian azzuwa-). Within the framework of this hypothesis (quite promising as such), one should not disregard some difficulties as far as the word-structure of the Semitic terms is concerned: both the loss of the word-initial vowel and the reduplication are present already in the earliest Sem. attestations.

Akkadian
sīsû - horse (CAD S 328, AHw. 1051)
The Akkadian word together with Ugr. ssw, s̀s̀w , Hbr. sūs and Syr. sūsyā are all related to each other, but the common source is usually thought to be foreign rather than Semitic
Ugaritic
ssw - horse (DUL 772)

Var. s̀s̀w. Cf. sswt ‘mare’. Of uncertain origin (cf. SED II No. 199), but, contra Watson 2007: 70, certainly not an Akkadism in Ugaritic (Kogan 2015: 359).

Amarna Canaanite
sú-ú-[sí-ma] - horse (plur. abs.) (DNWSI 795)
A gloss to ANŠE..MEŠ in EA 263.25.
Phoenician
ss - horse (Tomback 1978 231, Krahmalkov 2000 346)
HapLeg in KAI 26 A I 6-7: wpˁl ˀnk ss ˁl ṣs ‘I acquired one horse after another’ (see Gibson 1971 57).
Hebrew
sūs - horse (HALOT 746)
Deir Alla
ssh - horse (DNWSI 795)
Attested in 11.15 (šˁlt mlk ssh) in a difficult context (v. Hackett 1980 72).
Old Aramaic
ssyh - horse (DNWSI 795)
HapLeg in KAI 222A 22: šbˁ ssyh yhynḳn ˁl wˁl yš[bˁ] ‘seven mares will suckle a foal and he will not be sated’ (v. Fitzmyer 1995 80).
Official Aramaic
swsh - horse (DNWSI 795)
pl. swsyn, emph. swsyˀ
Demotic Aramaic
swsy - horse (DNWSI 1261)
Palmyrean
swsy - horse (DNWSI 795)
V. PAT 391 (ṣlm mrkb swsy ‘an equestrian statue’)
Nabataean
swsyˀ - horse (DNWSI 795)
V. Cantineau 123.
Jewish Palestinian Aramaic
sūsē - horse (DJPA 371)
det. sūsyā, pl. swswwn
Samaritan
sws - horse (DSA 574)
Jewish Babylonian Aramaic
sūsyā - horse (DJBA 794)
Syriac
sūsyā - horse (LSyr. 464, SL 986)
Mandaic
susia - horse (MD 322)
Cf. sisiata, var. of susiata ‘horses, mares’ (MD 329)
Maalula
sūsca - horse (GNDM 83)
Turoyo
susyo, səsyo - Hengst (stallion) (Kuipers 1983:130)
səsto ‘stute (mare)’ (RW 451)
Arabic
sīsiyy- - pony (AWSG 408)
Quoted as an Egyptian dialectal word (cf. BH 445), not attested in the available dictionaries of Classical Arabic. Arb. sws ‘to rule over people’ (BK 1 1164, LA VI 108) is often regarded as derived from the present root with a meaning shift from ‘to drive horses’ (e.g., Hommel 1879 45-6, 54); cf. especially Arb. Syr. sā́yes ‘take care of or heal a horse’ (Barthélemy 373)