From Sanskrit वज्र (vajra)
From 金 (kon, “mineral/material”) + 剛 (gō, “hard, tough, rigid &/or strong”)
金剛 (hiragana こんごう, romaji kongō) "unyielding," "unwavering" or "adamant;" lit. "the hard or mighty one"
- Buddhist term of Vajra, literally meaning both "Diamond" & "Thunderbolt," referring to the symbolic nature of both that of a diamond, (in that it can cut any substance, but can not, itself, be cut,) and that of the thunderbolt, (an irresistible force)
- Term referring both to the firmness of one's own spirit, and to the strength of one's own spiritual power
- A material object and 'device', a Buddhist ceremonial mace and symbol, a ritual tool and spiritual implement, believed to represent firmness of spirit and spiritual power; and also used as a short metal weapon, (originally a kind of fist-iron,) like a Japanese yawara, (which was actually inspired from this ritual item, vajra/kongō,) either one or two small, thick sticks which stick out about an inch from each side of the hand--usually used in pairs to initiate throws, bone breaks, and pressure point strikes
- (figuratively) Something extremely hard, of extreme metaphorical, metaphysical or immaterial strength
- (literally) Something extremely hard, of extreme literal, physical or material strength
- Short for 金剛石; (the actual mineral/gemstone of diamond).
Derived terms 
See also 
- 玉 (たま, tama,) "jade," "gemstones," or any sort of precious stone
- 宝石 (ほうせき, hōseki) "gemstone," "precious stone(s)"
- 晶 (しょう, shō) "crystal"
- 水晶 (すいしょう, suishō) "crystal" (quartz)
- 落雷 (らくらい, rakurai) a "thunderbolt," a "lightning strike"
- 稲妻 (いなずま, inazuma,) a "lightning bolt"
- 雷電 (らいでん, raiden) "thunder & lightning"
- 雷鳴 (らいめい, raimei) "thunder,"
- 雷神 (らいじん, raijin): "thunder god"
金剛 (traditional, Pinyin jīngāng, simplified 金刚)
- (figuratively) an object that is extremely hard and strong
- (Buddhism) vajra