A few words of Japanese origin, which described concepts or things unique to Japanese culture, are now used in English in a novel and creative way. For example, in Japanese myth, kamikaze was a divine wind which saved the Japanese by sinking the Mongolian navy. In the Second World War, a kamikaze was a Japanese pilot who flew his plane into an enemy ship on a suicide mission. Kamikaze is now a metaphor for any self-destructive act, as in kamikaze tactics, kamikaze approach. Another Japanese term which has undergone a similar meaning development is tsunami. Literally `harbour-waves', a tsunami is one or several large sea waves produced by an underwater earthquake or volcanic eruption. It is often used as a metaphor for a sudden increase or large volume of either concrete or abstract things, e.g. a tsunami of aid, of words, or of support. It can be compared to flood, deluge, tide, wave, and torrent which have the same metaphor. Words for different religions and faiths often develop adjectives which describe the particular qualities of their believers, e.g. That's not very Christian of you. Similarly, Zen, a branch of Buddhism, not only refers to a religion or philosophy, but, more loosely, a state of calmness or meditation. It is sometimes found in phrases like zen-like calm, with or without a capital.