Final answer:
The forked lines on lines representing relationships in an ERD are known as crow's feet, which symbolize a 'many' relationship between entities.
Step-by-step explanation:
The forked lines on the lines representing the relationship between two related entities in an entity-relationship diagram (ERD) are referred to as crow's feet. These symbols are used in ERDs to denote the cardinality of a relationship, specifically indicating a "many" relationship. For example, if a table called Authors has a one-to-many relationship with a table called Books, the line connecting Authors to Books will have a fork (crow's feet) near the Books entity to show that one author can be associated with many books.