Rhinoceros in Biblical and Cognate Languages

The evidence that the Hebrew word, Re'em, refers to the Aurochs is overwhelming.  Nevertheless, there are some who maintain the view that seems to have first originated with the second century translator of the Old Testament, known as Aquila of Sinope.  Apparently Aquila was a proselyte to Judaism, and a disciple of Rabbi Akiba.

As a side note, I found this fascinating detail regarding Masoretic vowel tradition in the Jewish Encylopedia entry on Aquila:

It is interesting to note that Aquila does not agree with the Masoretic punctuation in pointing the names of heathen gods (e.g.,  and , Amos v. 26) with the vowels of  ("abomination").

(source)

If this accurate, it confirms that the pointing of the Tetragrammaton with the vowels for "Lord" is similarly a way of highlighting the truly divine, rather than being the actual vowels.

Returning to our question, there is a Greek word for rhinoceros, it's ρινόκερως (rinokeros).  That's the word Aquila used, although the Septuagint did not.  Our English word is directly taken from Latin rhinoceros, which got it from the Greek.

The modern Hebrew word for rhinoceros is "קַרנַף" (kar'NUF).  However, the word karnuf was invented in the 20th century by Joseph Klausner, using the Hebrew words keren (horn) and af (nose).

Turning to other related languages, I found two main branches: one from the Sanskrit, the other from the Ge'ez. 

Ge'ez

• Ge'ez ሐሪሥ, ሐሪስ (ḥäriś, ḥäris, “rhinoceros”) 
• Arabic حَرِيش‎ (ḥarīš, “rhinoceros”) (apparently derived from Ge'ez)
• Other languages related closely to Ge'ez have similar words.

Sanskrit

On the other hand, Persian has the word کرگدن (karkadan), apparently from Middle Persian (klg /karg/, “rhinoceros; horn”) + (-dʾn' /-dān/, “bearer, holder”), ultimately from Sanskrit खड्ग (khaḍga, “rhinoceros; literally sword bearer”).

This word is similarly found in other languages:

• Arabic كَرْكَدَّن‎ (karkaddan, “rhinoceros”)
• Classical Syriac ܟܪܟܕܢܐ‎ (karkǝḏānā, “rhinoceros”)
• Sanskrit खड्गधेनु (khaḍgadhenu, “a female rhinoceros”)
•  Avar: гаргадан (gargadan)
• Middle Armenian: քարկարտան (kʿarkartan), քարկանտան (kʿarkantan)
• Turkish: gergedan
• Uyghur: كەركىدان‎ (kerkidan)
• Uzbek: karkidon

Looking through the Semitic Etymology dictionary, I only found three entries related to the rhinoceros:

Number: 2648

Proto-Semitic: *yaʕal- ~ ʕawāl- (?)

Afroasiatic etymology: Afroasiatic etymology

Meaning: 'mythological bull' 1, 'rhinoceros' 2, 'young of the elephant' 3

Akkadian: alû (elû) 1 'bull (as a mythological being)' Bogh, SB, Akkadogr. in Hitt. CAD a1, 377

Syrian Aramaic: yaʕlā 2 'unicornus, rhinoceros' Br 305

Tigre: ʕǝwal 3 'young of the elephant' ("in der Poesie auch von anderen jungen Tieren gebraucht") [LH, 477], ʔäwal [ibid., apud Munz.] (hardly connected with *ʕVwVl- 'young of an animal' which is attested in Tgr as ʕǝlu 'young of the donkey' [LH 450]; <*ʔawāl- with a variant form in ʕ- through contamination with ʕǝlu) ?

Number: 2654

Proto-Semitic: *ḥar(i)ŝ/ŝx ( ~ *Hawuraris)

Afroasiatic etymology: Afroasiatic etymology

Meaning: 'rhinoceros'

Syrian Aramaic: Cf. ḥarsūmā 'proboscis; labia bovis' Br 257

Arabic: ḥarīš- [BK 1 408]

Geʕez (Ethiopian): ḥariŝ, ḥaris, ḥoras, ʔarwe ḥoras [LGz 244]

Amharic: Cf. ʔawuraris 'rhinocéros' Baet

Number: 2655

Proto-Semitic: *karkadan- ~ *karkand-

Meaning: 'rhinoceros'

Syrian Aramaic: karkǝdonō Brock. 346b

Arabic: karkaddan-, karkadann- [BK 2 888]

Geʕez (Ethiopian): karkand 'unicorn, rhinoceros' LGZ 291

The Assyrian dictionary only offered this:

From my standpoint, the issue here is not just that the words for "rhinoceros" are nothing like Re'em, but that even the one Proto-Semitic word that might refer to a rhinoceros independent of the Ge'ez and Sanskrit streams seems to have mythological connotations.  Arabic stands at a cross-roads between the two major streams and adopts names from both languages, but there seems to be no uniquely Arabic word distinct from the Ge'ez and Sanskrit.  

There are several Biblical Hebrew words with similarity to the "haris" root (Strong's Nos. 2789-2802, for example), but the closest seems to be 2793 "choresh" (חרֶשׁ), which has no obvious connection to rhinoceroses as such. Similarly with the other options.

What's the best explanation for this lack of word for rhinoceros among the Hebrews?  

This is the current range of the Rhinoceros.  Wooly rhinoceros remains have been found in the British isles and Siberia.  The most interesting variety of rhinoceros for the rhinoceros/unicorn identification is the Indian rhinoceros.  According to Brittanica: "The Indian rhinoceros previously occupied an extensive range across northern India and Nepal from Assam state in the east to the Indus River valley in the west." (source) 

The most likely explanation for the lack of a Hebrew word for rhinoceros is the absence of rhinoceroses in Canaan during the time period from the 15th century B.C. onward.  While I doubt some of the dating methods used, this article summarizes the current naturalistic view on the presence of rhinoceroses in Canaan: "Said Prof. Amos Frumkin, director of the Hebrew University’s Cave Research Center: 'Rhinos haven’t been seen in the land of Israel in the last twenty or thirty thousand years...'." (article describing the find of ancient rhinoceros remains in Samaria)