What is a compound word?

A compound word is a word that is composed of two or more separate words that are combined to make a new word.

For example, combine dragon and fly to make the word dragonfly which has a completely different meaning than either of the original words.

One takes a root word, like the example "fly" and adds a descriptive word such as "dragon" to get dragonfly. In a related question, "treetop" applied.

A word with two parts (for example, butterfly is a compound word because is has butter and then fly) others could be:

paperclip, newsstand, newspaper, eyelid, bedrock, ladybug, pigtail, pigpen, flowerpot, handbag, bedtime, handshake, ect.