“Genki” (元気) is the one Japanese word that consistently slips into my English. It means, in casual conversation, “pep, good energy,” and is the small-talk answer to the question “How are you?” I reach for it in English when I see someone up and about, lookin’ good after being sick or stressed.

Anyway, Matt Treyvaud’s got a really cool essay on the history of the word. Interesting, especially for the non-Japanese speaker, because it illustrates how (and why) words are spelled differently over time, as their connotations shift.