The word Cherubim in the Bible
Cherubim are supernatural creatures associated with the throne of God. One of them would be called כרוב (kerub).
The words Cherub and Cherubim occur about a hundred times in the Bible but descriptive imagery of Cherubim is scarce. Cherubim appear as ornamentation in the tabernacle (Exodus 26:1) and temple (1 Kings 6:23, 6:29, 7:29) but the only full descriptions of a Cherub's appearance occurs in Ezekiel 1 and 10 (actually, the word cherub doesn't occur in chapter 1). But Ezekiel's elaborations on an entity that featured profusely as decoration suggests that these Cherubim weren't standard.
When God instructs Moses to build the Cherubim for the Mercy Seat, He doesn't specify the fact that they have wings but refers to their wings as if everybody already understood that Cherubim are always winged (Exodus 25:20). We don't know how many wings Moses' Cherubim were supposed to have but Ezekiel's Cherubim have four each (1:6).
Ezekiel's Cherubim have four faces each; one human, one bull, one eagle and one lion (1:10). These four animals return in the vision of John the Revelator; their cry "Come" ushers the four horsemen (Revelation 4:7, 6:1).
This, plus the fact that Ezekiel's Cherubim seem hybrids of earthly creatures, leads scholars to believe that the Biblical Cherubim were part of a sculptural genre that was popular in Assyria and Canaan; images of bull-lion, lion-faced and eagle-winged creatures.
Israel didn't exist in a cultural vacuum and Solomon's temple certainly had its examples and derivatives abounding in the surrounding nations. Still, a resemblance doesn't mean equality, and the purpose and essence of the Cherubim is probably better explained by the Biblical canon than by a Canaanite artistic genre.
Cherubim are stationed to the east of Eden, to guard the way to the tree of life (Genesis 3:24), they seem to carry a firmament with on it the throne of God (Ezekiel 1 & 10), and sometimes they serve as some kind of singular transportation device for God (2 Samuel 22:11, Psalm 18:10).
Etymology of the word Cherubim
The word כרוב (kerub) is without root or equal in the Hebrew language—or at least, in the Hebrew language preserved in the Bible—so we don't exactly know what it might have meant to the Hebrews. It might be that, even for them, the word Cherub was just a name without further meaning. But that's very rare in the Bible since most names and words are part of groups of words that all tell something about the other words' meanings. It's more plausible that the word kerub belongs to a root verb that was used by the Hebrews but never made it into the Bible. Chasing this allusive root verb, scholars turn to cognate languages.
BDB Theological Dictionary reports the root of the word kerub missing in action, but notes that the Assyrian verb karabu means to be gracious or to bless. Curiously enough, the Hebrew verb for exactly that is the mirror image of our missing root, namely the verb ברך (barak—the root of the name Baruch). The adjective that comes from the Assyrian verb karabu is karubu, which means great or mighty. Then there is the Assyrian word kiribu or sedu, which is the name of the famous winged bull in Assyria, but, says BDB, kinship with kerub has not been verified. There are even some who connect ברך (kerub) to the Persian word giriften (the mythological Griffin) but, says BDB, this lacks evidence and probability.
Some Hebrew letters can be exchanged without changing the meaning of the word much but all three consonants of the word kerub are very stable. There are no sound recordings from the classical times but the letters כ (kaph) and ק (qoph) probably sounded somewhat similar. And even though there no two words with the same meaning, with one spelled with a kaph and the other with a qoph, the Hebrew verb קרב (qarab I), meaning to come near or approach, has a Assyrian cognate karabu, which is highly similar to the word mentioned above as possible source of the word kerub. Another Hebrew root קרב (qarab II) is unused and can't be translated, but it's cognate to the Assyrian word kirbu, meaning midst:
Formally, the meaning of the word Cherub is obscure, but to a Hebrew audience it may have meant Mighty, Approacher, Blessing, or Within.
Also see our article on Seraphim.