also: しいこう
noun
supreme filial piety
A formal, somewhat literary term for the highest degree of filial devotion, often used in Confucian or historical contexts.
彼の至孝な行いは村中で称えられた。
His acts of supreme filial piety were praised throughout the village.
孝行 is the common word for filial piety; 至孝 is a rarer, more emphatic term meaning 'supreme' or 'utmost' filial devotion.
From 至 (utmost) + 孝 (filial piety). The exact historical derivation is uncertain, but the compound follows classical Chinese patterns.