The term 'make up one's mind' is a phrase used to describe the act of making a decision. The crossword solutions for this phrase are DECIDE (6 letters) and OPT (3 letters). DECIDE means to come to a conclusion after considering all options, while OPT means to choose or select from a range of possibilities. Therefore, the phrase 'make up one's mind' can be interpreted as making a decision after considering all available options.