No precise equivalent exists in the English language for ch'i, the spiritual "energy" or, literally, "vapor" that forms all matter, including human life.
Ch'i is the universal breath of energy that gives us our material existence, and is reflected in our appearance or ch'i-ch'ing ("energy-image").
Excerpted from The
Spirit of the Chinese Character: Gifts from the Heart,
Barbara Aria with Russell Eng Go, Chronicle Books, 1992