UNICORNS!

Using more updated version with modern English the word used there is oxen. Though some have speculated rhino, as well.

The KJV is correct.
A long time ago I came up with 5 possibilities. It's too late to do a repeat study to answer the Q now. Just rest assured that it simply refers to a beast with one horn. Those who mock God's Word like to throw in a my little pony rainbow unicorn that flys, as if this term is some sort of proof that our Bible can't be trusted. All they are doing is demonstrating their willfull ignorance. You have asked a good question and it's good to be familiar with the answer since there are atheists that attack it frequently.

There are extinct and existing animals that fit that term. I'm sure you can think of one that you'd see at a large zoo.

Those in a museum would be a variation of a cerapod. The well known Triceratops has three horns, but there were a variety of variations. There was a large single horned mammal that also fit that term. It's commonly called the Siberian Unicorn.
It's remains have been found from eastern Europe to eastern Asia. Some sources describe it as anywhere from several times the size of a rhino to larger than an elephant. Here's one fairly short video with cgi graffics. Take anything stated by paleontologists, or archaeology as speculation. All dates of dinosaurs for instance are mere fabrications.

Unicorn

reh-ame', reh-ame', rame, rame

From H7213; a wild bull (from its conspicuousness): - unicorn.

Conspicuousness

Standing out so as to be clearly visible which would be the horn.

The bull is known for its strength, and no fear, and bold.

Job 39:9 Will the unicorn be willing to serve thee, or abide by thy crib?

Job 39:10 Canst thou bind the unicorn with his band in the furrow? or will he harrow the valleys after thee?

Which is why God told Job can you get the bull to do what you want because of their demeanor.

Deuteronomy 33:17 His glory is like the firstling of his bullock, and his horns are like the horns of unicorns: with them he shall push the people together to the ends of the earth.

Which we know bulls can have a bad temperament.

The unicorns in the Bible are not described as those loveable mythical creatures.

Psalm 22:21 But my horn shalt thou exalt like the horn of an unicorn: I shall be anointed with fresh oil.

Psalm 92:10 But you have exalted my horn like that of the wild ox; you have poured over me fresh oil.

The same message one referring to a unicorn, and one of a wild ox.

Numbers 23:22 God brought them out of Egypt; he hath as it were the strength of an unicorn.

Numbers 24:8 God brings him out of Egypt and is for him like the horns of the wild ox.: he shall eat up the nations, his adversaries, and shall break their bones in pieces and pierce them through with his arrows.”

The same message one referring to a unicorn, and one of a wild ox.

Huh. Weird

That would be about right. Not the mythical creatures commonly seen today in various illustrations.

10k pound rhino.
Impressive.

Oxen is already mentioned some 95 times in scripture. They are not the same nor should oxen be a substitute. The word unicorn is correct. We should not let the culture dictate the word of God.

Rhinoceros unicornis (one-horned). This isn’t that difficult a concept.

As for the KJV being “correct”, it’s an irrelevant statement. Most 17th century English people would never have seen, let alone heard of, a rhinoceros. When most modern people read “unicorn”, they don’t think “rhino” so the change in meaning makes the translation misleading.

As what other posters have indicated - Biblical unicorn = rhino; a single horned animal. More common in rivers in the ancient Middle East/North Africa than it is today. Not so much in Europe so when texts were translated they went with an animal they knew, even if it was just mythical.