The crossword solution for the term LEAST LIKELY TO CRACK is SANEST, which is a six letter word. Sanest is an adjective that means most sensible, rational, or level-headed. It is often used to describe someone who is not easily influenced by emotions or stress and is able to remain calm in difficult situations. Therefore, the phrase LEAST LIKELY TO CRACK can be used to describe someone who is the most stable and reliable in a given situation.