至孝

zhìxiào
  1. (literary) extremely filial
  2. extremely filial

Wiktionary

Entry Composition

=1 至 zhì
  1. to arrive
  2. most
  3. to
  4. until
=1 至 dié only used in 單至／单至
2 孝 xiào
  1. filial piety or obedience
  2. mourning apparel