Is caterpillar a compound word? Cat er pillar

If it isn't what would the word be for 3 words

Not an assignment

The word chatepelose is derived from the Latin phrase catta pilōsa, which really did mean "hairy cat". Therefore "caterpillar" originated as a compound word, although the modern English word is not a true compound ... A caterpillar can mature into either a butterfly or a moth, depending upon the species