"The earliest meanings of unique when it entered English around the beginning of the 17th century were “single, sole” and “having no equal.” By the mid-19th century unique had developed a wider meaning, “not typical, unusual,” and it is in this wider sense that it is compared: The foliage on the late-blooming plants is more unique than that on the earlier varieties. The comparison of so-called absolutes in senses that are not absolute is standard in all varieties of speech and writing." Based on the Random House dictionary...