Phrase/Clause + と言う
Verb + と言う
Adj-i + と言う
Noun + だ + と言う
Adj-na + だ + と言う
The grammar structure ~と言う is used to express:
Indirect speech: Reporting what someone has said or is saying indirectly (note that nouns and na-adjectives require だ in this case).
Hearsay: Indicating information heard from someone else or general hearsay.
Definitions/naming: Defining or naming something by saying "it is called."