… a Qualisign is any quality in so far as it is a sign. Since a quality is whatever it is positively in itself, a quality can only denote an object by virtue of some common ingredient or similarity; so that a Qualisign is necessarily an Icon. Further, since a quality is a mere logical possibility, it can only be interpreted as a sign of essence, that is, as a Rheme.
A Qualisign is a quality which is a Sign. It cannot actually act as a sign until it is embodied; but the embodiment has nothing to do with its character as a sign.
As it is in itself, a sign is either of the nature of an appearance, when I call it a qualisign; or secondly, it is an individual object or event, when I call it a sinsign (the syllable sin being the first sillable [sic] of semel, simul, singular, etc); or thirdly, it is of the nature of a general type, when I call it a legisign.
The qualisign […] has no identity. It is the mere quality of an appearance & is not exactly the same throughout a second. Instead of identity, it has great similarity, & cannot differ much without being called quite another qualisign.
A qualisign is an aspect, impression, or other priman significant regardless of its parts or of anything else simply because it involves the very character signified.