Qualisign is a term used by Charles Peirce in his theory of signs (or semeiotic) to designate a kind of sign. Two other kinds of signs he identified are: Sinsign and Legisign). For a good introduction to Peirce's semeiotic see Part 2, "Meaning is a Triadic Relation", of John K. Sheriff's book: The Fate of Meaning: Charles Peirce, Structuralism, and Literature (Princeton, N.J.: Princeton University Press, 1989). Here's a quote from Sheriff where he quotes Peirce:
"A Qualisign," according to Peirce, "is a quality which is a sign. It cannot actually act as a sign [be represented] until it is embodied [in a triad of sign-object-interpretant]; but the embodiment has nothing to do with its character as a sign"*. In the beginning was a sign, and that sign was with a quality, and that sign was a quality. In Peirce's cosmogonic philosophy and sign theory, all reality and signs have evolved from qualities. (pp. 68-69)

*The Collected Papers of Charles Sanders Peirce, vols. 1-6, ed. Charles Hartshorne and Paul Weiss, 1931-1935; vols. 7-8, ed. A. W. Burks, 1958 (Cambridge: Harvard University Press), vol. 2, para. 244.