Morse code

color or pattern that aids in camouflage; camouflage

training in seclusion on a mountain

to train in seclusion on a mountain

wastepaper basket

silver-stripe round herring, blue sprat, kibinago; a small marine fish, Spratelloides gracilis

the Four Books and Five Classics

coding theory

adamantine strength: / the firmness of one's own spirit, and the strength of one's own spiritual power. / (figuratively, literally) something extremely hard, of extreme strength.

(Buddhism) a square- or octagonal-sided walking stick used by practitioners of 修験道 (Shugendō) or pilgrims / (Buddhism) a vajra (ritual club) possessed by a yaksha