The term 'Principal Parts' refers to the three main parts of a verb in Latin: the present, perfect, and future. These three parts are used to form the conjugations of a verb, which are the different forms of a verb that indicate person, number, gender, tense, mood, and voice. The term 'BODIES' is related to Principal Parts, as it is the plural form of the word 'BODY, ' which is used to refer to the conjugations of a verb.