noun
entering elementary school a year later than usual
Obsolete colloquial term for the practice of delaying a child's entry into elementary school by one year, often due to the child's birth date or developmental readiness. Contrasts with 早上がり (はやあがり), which means entering a year earlier.
See also: 早上がり (はやあがり)
昔は、遅上がりで小学校に入学する子もいた。
In the past, some children entered elementary school a year later than usual.
遅上がりは、今ではほとんど見られない制度だ。
Entering school a year late is a system rarely seen nowadays.
Means entering elementary school a year earlier than usual; the opposite of 遅上がり.
Compound of 遅 (おそ, 'late') + 上がり (あがり, 'entering school'). The exact historical derivation is uncertain, but it reflects the practice of delaying school entry.