Final answer:
The phrase 'sea change' denotes a substantial transformation in someone's attitude, circumstances, or character, used figuratively to describe significant life changes such as a change in personal beliefs or major life decisions.
Step-by-step explanation:
The phrase “a sea change” originally comes from Ariel’s song in William Shakespeare’s play “The Tempest,” where it refers to a literal transformation caused by the sea. In modern usage, to say that someone or something has experienced a sea change typically means they have undergone a significant transformation or metamorphosis in character, attitude, or circumstance. This could involve a changed attitude towards someone, a major life decision like a change of major, or a significant event such as making a team, undergoing a personal realization, moving to a new country, becoming fluent in a new language, or reassessing admiration for someone. The key element is the substantial and often profound nature of this change.