Pretty late on this, but just in case, a few of points:
someone's already sort of mentioned this, but your first example (defining "red"), is by ostension, not by extension. Defining something by extension, especially something like "red", would require pointing out an infinite number of things.
You were probably just careles in your choice of words, but "the neural pattern (in my temporal cortex) that inspects an incoming signal from the visual cortex to determine whether or not it is a tiger" is a good example of Betty Crocker's Theory of Microwave Cooking (cf. http://books.google.ca/books?id=9JGOmd66jGsC&pg=PA121&lpg=PA121&dq=churchland+betty+crocker+microwave&source=bl&ots=5JDuIkAIe6&sig=6KK3pE7xUE12U5O5C5DKaP2gz_c&hl=en&ei=HRsbS46YDsWKlQf7_rm6BA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CA0Q6AEwAA#v=onepage&q=&f=false
your final point about redefining words "any way I like" being the same as changing/reassigning beliefs is exactly right...our words can only "mean" our intensions of them, and since we can't/don't communicate intensions, the chain ends there.