海内hǎinèi古人认为我国疆土四面环海,因此称国境以内为海内{(people in ancient times thought China was surrounded by four seas, hence this phrase) within the four seas, a phrase meaning throughout the country, derived from the ancients' belief that China is surrounded by seas on four sides}: 风行～{prevalent throughout the country, popular all over the country}|～孤本。{only extant copy (of a book) in the country}€