2 Peter 2:12 But these, as natural brute beasts, made to be taken and destroyed, speak evil of the things that they understand not; and shall utterly perish in their own corruption; [kjv]
ουτοι δε ως αλογα ζωα γεγεννημενα φυσικα εις αλωσιν και φθοραν εν οις αγνοουσιν βλασφημουντες εν τη φθορα αυτων και φθαρησονται [gnt]
2:16 But was rebuked for his iniquity: the dumb ass speaking with man's voice forbad the madness of the prophet. [kjv]
ελεγξιν δε εσχεν ιδιας παρανομιας υποζυγιον αφωνον εν ανθρωπου φωνη φθεγξαμενον εκωλυσεν την του προφητου παραφρονιαν [gnt]
The modern Greek word
"άλογο" (A-lo-go) ≈ "horse", in ancient times, came from the phrase
"άλογο ζώα" (A-lo-go ZO-a) ≈ "unspeaking/unthinking animal" and usually referred to a war horse (e.g., pulling a chariot, used in a mounted calvary attack, etc.). These were magnificent animals, trained to do whatever they were led to do by their rider/master - even to their own destruction.
The Greek for "
ass" is that of a pack animal doing work. The translators used the
OT (Old Testament) word rather than the word Peter wrote and appeared to mean to keep the military animal analogy consistent and meaningful.