よほど and its variant よっぽど are adverbs meaning “very,” “greatly,” or “to a large extent.” They indicate that something reaches an unusually high degree, often stronger than the speaker’s ordinary expectation. They commonly modify an adjective or verb predicate, and よほどの + noun describes an unusually serious or considerable thing. よほど is suitable in neutral and formal writing, while よっぽど is more conversational but is also widely used in speech.