בהמות • (transliteration needed) m
In form it is a plural of בהמה, but in Job 40:15-24 the word is accompanied by verbs and adjectives in the singular (describing a big and powerful beast).
This fact can be explained either be assuming a pluralis excellentiae, a method of expressing greatness by pluralizing a noun, or by assuming a word in the singular.
The second approach is taken by the Midrash (Leviticus Rabbah 13:3), describing the בהמות as a great beast, and probably also by the Peshitta, transliterating the word rather then translating it: ܒܗܡܘܬ.
(*pꜣ-jḥ-mw), an unattested word that would have meant “the ox of the water”, i.e. hippopotamus, from pꜣ (“definite article”) + jḥ (“ox, cattle”) + mw (“water”) in a direct genitive construction; for the pronunciation, cf. the later Coptic descendants ⲡ- (p-) + ⲉϩⲉ (ehe) + ⲙⲟⲟⲩ (moou).
בְּהֵמוֹת • (behemót) m
- (Biblical Hebrew) Meaning unknown, perhaps a water ox, that is, the hippopotamus or Nile horse.
- behemoth, a great and mighty beast.
- H930 in Strong’s Exhaustive Concordance to the Bible, 1979
- Brown, Francis; Driver, Samuel Rolles; Briggs, Charles Augustus (1906) A Hebrew and Aramaic Lexicon of the Old Testament, Oxford: Clarendon Press
- Koehler, Ludwig; Walter, Baumgartner (1994–2000) The Hebrew and Aramaic Lexicon of the Old Testament, Leiden: Brill