I think that Ayn Rand and Bob have a particular problem in common - the tendency to insist that their own pet definition of a word is the only proper definition. I believe it is better to accept that words have more than one commonly used definition and specify which particular definition of a word we are using in any given statement. Despite the fact that words have more than one meaning we should be able to understand another person's statement if we understand which particular definition they are using for each word in the statement.
Another point I'd like to bring up: It is important to understand that when one person makes the statement "X is true" and another person makes the apparently contradictory statement "X is false" the statements do not actually contradict each other unless both people are using the term X to mean the same thing. Here is an example to illustrate that point: If I say, "There is a bat in the dugout" (meaning a baseball bat) and you say, "No, there's no bat in the dugout" (meaning a flying rodent) your statement would not contradict mine. Though we both would be using the same word, we would be using different meanings so our statements would have independent truth values.