A firm decision maker is someone who is able to make decisions that are well thought out and have a lasting impact. This person is often seen as a leader in their field and is usually dressed in a SUIT, which is why the crossword solution for this term is 'SUIT'. A firm decision maker is someone who is able to make decisions that are based on facts and research, rather than emotion or opinion. They are also able to take into account the opinions of others and make decisions that are beneficial to all parties involved.