I originally did not intend to post to this thread, but since it has been revived, I figure I should make a point that none of the posters above seemed to grasp, or at least bother to make themselves (it was suggested in the usage note given by Merriam-Webster, which was cited by KidCharlemagne, but it was a bit vague):
There are indeed such things as “absolute” adjectives, but they are not words like perpendicular or exact or even universal. They cannot be used with less, more, least, or most, though they can be used with almost (the relevance of which word to the matter I must assume to be a complete contrivance by the OP). For a word to be absolute it must contain some implication of quantity.
The first two definitions for “unique” given by M-W are
Both of these synonyms are examples of absolutes. It is not only incorrect from a prescriptivist view, but also from that of common sense, to say “more sole” or “more unequaled,” because these adjectives already express the degree to which they are true: sole containing the number one, and unequaled containing the number zero. To use the modifiers “less” or “more” with them would be as illogical as saying “less two” or “more three.”
When unique is used in these senses, the case is the same. As we all know, however, unique is very seldom used in these senses today, although I have encountered a few instances of it in literature from roughly a century ago. Used in the modern sense, unique is not an absolute.
I said that universal is not an absolute because, even though it does seem imply a fairly strict idea, its usage has come to imply a more general one, and hence “more universal” is capable of having a distinct meaning, unlike “more sole.” Ultimately usage, and therefore common sense, must dictate what is correct and what is not.
