Among the otherwise unknown concepts of the traditional Ethiopian astronomy there are two apparently Greek notions, kekros and kentros. In fact, none of them is witnessed by the Greek sources. Even the word κέντρον, being an important term in Greek astrology, was never used, in the available Greek texts, with a technical meaning similar to that of Ethiopic kentros (Neugebauer, 1979, p. 175).
Otto Neugebauer (1979, pp. 175-177) provided the most complete description of usage of both terms in Ethiopic but he was unable to propose any etymology. The basic meaning of kekros is 1/60 and the basic meaning of kentros is 1/30 of some (different) intervals of time.
As it was demonstrated elsewhere (Lourié, 2010, pp. 419-423), the term kekros goes back to Akkadian kukkaru through a lost Greek intermediary (*κέκρος). The basic meaning of kukkaru is a circle (disc) with sexagesimal partition implied; Ethiopic kekros became the name of each one of its sixty parts. Moreover, the Ethiopic term gize “time” in technical meaning (“two hours”) is (pace Neugebauer) a part of a terminological system ultimately of Mesopotamian origin corresponding to Akkadian bēru.
Now I would like to demonstrate that the term kentros is also a part of the same terminological system of Mesopotamian origin accepted in Ethiopia through a lost Greek intermediary. The word itself is not Akkadian and is obviously the Greek word κέντρον (“horn”, “centre” etc.) with the incorrect masculine ending -os instead of the neuter ending -on. In Greek, we presently do not know its usage related to the number 30. However, it is a priori likely that the word kentros, being a part of the terminological system of Mesopotamian origin, has some Akkadian prototype, too. It is especially likely because the number 30, being one half of 60, is also an important number in the sexagesimal number system.
Indeed, we have in Akkadian several words with the meaning “half.” What is especially important to us, all of them are used as well as the equivalents of Sumerian ba-aEŠ, i. e. the sign 30: mišlu, muttatu, zūzu, and bamtu (Reiner, 1968, p. 190). Only one of them, mišlu, has also the meaning “midpoint, center” (CAD m2, pp. 126-129), that is, the same meaning as Geek κέντρον. In different dialects of Aramaic the same root mšl is known with meanings “fork” (Sokoloff, 2002, p. 335; Brockelmann—Sokoloff, 2009, p. 849) and “awl, punch” (Payne Smith, 1903, p. 307), also close to the basic meaning of the Greek word (“horn”).
Therefore, in Akkadian mišlu, we have a term combining the meanings “30” and “midpoint, center,” exactly in the same manner as does the Ethiopic avatar of Greek κέντρον. Mišlu had the meaning of a unit implying trigesimal partition, being, in turn, one half of a larger unit implying sexagesimal partition (kukkaru). Ethiopic kentros is the name of each one of these thirty parts, in the same manner as Ethiopic kekros is the name of each one of the sixty parts of the corresponding unity. The role of a Greek intermediary in this passage of the term kentros from Akkadian to Ethiopic is rather obvious. Therefore, we have to admit one more meaning of the Greek term κέντρον in the Hellenistic period or earlier, although unattested in the texts preserved in Greek.
The source of borrowing of kentros remains obscure. Neugebauer’s hypothesis that this notion is implied in an Aramaic manuscript of the Astronomical Book of Enoch from Qumran (4Q211, fr. 1, cols. ii-iii) (Neugebauer, 1979, p. 169), although supported by Matthias Albani (1994, p. 62) and Jonathan Ben-Dov (2008, p. 195), is now proven to be false by Henryk Drawnel (2011, pp. 413-419).