Corresponds to the anterior. (Costomediastinal) line of pleural reflection. 2. It is deeply notched in the left lung posterior. to 5th costal cartilage by the pericardium costal cartilage by the pericardium. and extends vertically downwards to form. Lingula.
Generally speaking, a principle is a rule, standard, or belief of one kind or another. As an adjective, principal means âmost importantâ, while a principal is â generally speaking â a person who is most important in a particular organization or group.
Princeton's WordNet(4.50 / 4 votes)Rate this definition: 1  principal(noun) the original amount of a debt on which interest is calculated. 2  principal, school principal, head teacher, head(noun) the educator who has executive authority for a school. 3  star, principal, lead(noun) an actor who plays a principal role.