Damn the technicians for being so technical.
Probably the second worst translation of the Chinese phrase "tai chi" I have ever heard, although it is actually the most common translation. While in China I am sure the phrase is easily understood for what it means, it's translation to English has always been marred by an attempt to convey the same meaning and yet retain the brevity the phrase has in its native language. Intellectually, the first worst translation I have ever heard, Supreme Pole (Boxing), almost does a better job of giving a brief translation, but sounds horrible.
Tai Chi (or Taiji) is a component of traditional Chinese philosophy. Tai Chi Chuan is a martial art based on that philosophy. The idea goes like this:
First, there was wu chi. Wu chi means "without ultimate" or lacking extremes. Lukewarm as opposed to hot and cold.
From wu chi comes tai chi. Tai chi meaning... you guessed it: supreme ultimate, or having greatest extremes. Hot and cold.
From tai chi comes yin and yang, and lots of other stuff after that, and then tai chi is said to eventually return to wu chi but-that's-beyond-the-point
So the important thing to note is that tai chi essentially means the two greatest differentiated parts. HOT AND COLD. Not Supreme Ultimate, not Strongest Chi Energy, not Greatest Greatest.
Now, you will excuse me while I go practice some Two Greatest Differentiated Parts Boxing Style (Taijiquanfa).