Refers to the hard outer shell of animals such as crabs, turtles, and tortoises. Carapace is the upper shell, plastron the lower.
A crab's shell is very hard.
Figurative use comparing a person's back to a shell, often implying a broad, sturdy, or experienced back. Common in expressions like 甲羅を経る (to gain experience).
years of experience
Metaphorical extension from the shell/back sense, referring to accumulated experience or expertise. Often used in set phrases like 甲羅を経る.
The skill of a veteran craftsman is impressive.
The turtle pulled its head into its shell.
He has a thick skin from years of experience.
Standard kanji spelling. The kanji 甲 and 羅 are ateji (phonetic).
Kana spelling is common in everyday writing, especially when the kanji are not needed.
The kanji 甲 (armor, shell) and 羅 (gauze, thin silk) are used phonetically (ateji) for the reading こうら. The word itself is of native Japanese origin, with the exact derivation uncertain.