The prefix "dys-" is used to indicate something abnormal, bad, painful, or difficult. It can be added to the beginning of a word to change its meaning. For example, "dysfunction" means abnormal functioning, "dyslexia" refers to difficulty in reading, "dyspepsia" means painful digestion, and "dysphoria" refers to a state of unease or dissatisfaction. Therefore, all the given options - abnormal, bad, painful, and difficult - can be associated with the prefix "dys-".