i have an extensive background in linguistics and taught it before at no time was there ever a compound in english in which they were two words compounds are single words not phrases the whole concept of compounding is merging two words together as one by definition a compound is a lexeme and lexemes do not have spaces in the middle of them an item with a space is a phrase as i proved above it does not many sources say otherwise there was a whole section devoted to listed references look under scope and you can see where it lists references provided