A compound modifier consists of two words connected by a hyphen, which act together like one adjective. Usually, compound modifier words could be understood as individual modifiers or nouns, so the hyphen is required to clarify the function of the words.
Consider the sentence below:
In the sentence above, it sounds like you shouldn’t take down any load that is holding up a wall. A hyphen should be inserted between load and bearing, so the reader understands not to take down any walls that are holding up a load:
Look at the following examples of sentences featuring compound modifiers connected by hyphens: