The term SETS (AGAINST) can be broken down into two crossword solutions: PITS (4 letters) and OPPOSES (7 letters). PITS is a noun that refers to a hole or depression in the ground, usually with steep sides. It can also refer to a trap or a difficult situation. OPPOSES is a verb meaning to be against or hostile to something. It can also mean to compete against or to resist. Together, these two words suggest a sense of opposition or conflict.