Subject matter is the main idea or TOPIC of a piece of writing, conversation, or other form of communication. The crossword solutions for this term are CONTENT (7 letters), CONTENTS (8 letters), Noun (4 letters), TOPIC (5 letters), THEME (5 letters), SUBSTANCE (9 letters), and AREA (4 letters). CONTENT refers to the information contained in a text, while CONTENTS is the list of topics included in a book or other publication. A Noun is a word used to identify a person, place, thing, or idea. A TOPIC is a subject that is discussed or written about, while a THEME is the central idea or message of a work. SUBSTANCE is the material that makes up something, and AREA is a particular geographical region or field of study.