noun
boarding school
A school where students live during the term. The term is straightforward and neutral.
彼は寄宿学校に通っている。
He attends a boarding school.
その寄宿学校は規律が厳しい。
That boarding school has strict discipline.
全寮制 refers to a full-boarding system or institution, often used as an adjective (全寮制の学校). 寄宿学校 is the more common, concrete noun for a boarding school.
Compound of 寄宿 (boarding, lodging) and 学校 (school). The exact historical derivation is uncertain, but the components straightforwardly combine to mean 'boarding school'.