Genki is the first Japanese word most learn upon arriving in the country. It’s fun, it’s useful, it’s easy to pronounce. It means “energy, pep, health,” and you can usually find someone on hand to explain that the kanji 元気 mean “original spirit” or similarly, are indicative of a positive worldview in which the default state for a human is to be in good health and high vigor.

This may be what genki means today, but the history of the word is far more complex. A 1988 paper by Ran Chikumin (栾竹民), modestly entitled “Some thoughts on three spellings of genki” (「減氣・験氣・元氣」小考), goes back thousands of years to lay out the facts for us:

• The term 元気 was used in ancient China, but not to mean “health” or “vitality”. Instead it referred to a ubiquitous, primal energy that made up all things: “元氣者、天地之始、万物之祖” (“Genki is the beginning of heaven and earth and the ancestor of the myriad things”).
• In Japan, the word 減気 (also pronounced genki) was invented by Heian scholars writing in Chinese to describe a reduction (減) in the energy (気) of an illness. 減気, which bore no relation to the much less common 元気 despite the coincidental homophony, soon spread from straight kanbun to other forms of writing. And so, for example, you find Dōgen in the 13th century saying things like 「種々ニ療治セシニ依テ少キ減氣アリシカレドモ」 (“Following a range of treatments, there was some remission in his illness, but…”). In other words, unlike ancient 元気, classical 減気 was very close to the genki of today.

• Sometime in the Muromachi period, a trend began towards writing genki with the characters 験気. These had the same pronunciation but had previously been used for a different genki meaning a positive effect observed after ritual or prayer.
• By the Edo period, 験気 had more or less taken over from 減気 as the preferred spelling for genki as in “get well”. It had also obtained an extra, related meaning: “be well”, without any implied recovery from an unwell state.

• Later in the Edo period, the spelling changed to 元気, bringing the modern meaning and spelling together for the first time. Ran suggests that this may have been for a combination of reasons: the shift in meaning away from the subsiding of an illness and towards health in general, influence from dictionaries and other authoritative texts (including medical texts), and most intriguingly, collateral damage from the ongoing Neo-Confucian debate over whether ki (気, energy) and ri (理, principle) were of equal importance (理気二元論), or whether ri was secondary to the primal ki (気一元論).

In other words, Ran argues, modern genki is a chimera, a relatively recent combination of a straightforward word that describes illness receding and a philosophical concept with millennia of metaphysical baggage. To the extent that it has a deep philosophical meaning, it acquired it by phonetic accident.

Never forget: a kanji is a lie.