The term 'SUBSIDIARY math theorem' is composed of two crossword solutions: 'lemma' (5 letters) and 'SUBSIDIARY' (9 letters). A lemma is a proven statement that is used as a stepping stone to prove another statement. It is often used in mathematical proofs, and is a type of SUBSIDIARY theorem. SUBSIDIARY theorems are related to the main theorem, but are not necessarily necessary for its proof. They are used to provide additional information or insight into the main theorem.