noun, na-adjective
spaciousness; vastness; expansiveness
Describes physical or metaphorical breadth and openness; somewhat literary.
その公園の広闊な芝生は、多くの家族連れで賑わっていた。
The park's spacious lawn was bustling with many families.
彼の広闊な知識にはいつも驚かされる。
I am always amazed by the vastness of his knowledge.
Compound of 広 (wide) and 闊 (spacious, open). The exact historical derivation is uncertain, but the combination naturally conveys vastness.