Break the word down by its prefixes and suffixes and determine their meanings. For example, cardiorespiratory has the prefix 'cardio' which means heart. You can also try to spot root words in the word and determine their meanings, such as the word 'respire' in cardiorespiratory, which means to breathe. Give these clues, one can assume that cardiorespiratory is anything having to do with the lungs and heart, such as the cardiorespiratory system of the human body.
