In what Lyotard conceptualized as the “post-industrial” and “postmodern” age, knowledge is no more a unified entity but a fragmented complexity. This paper tries to come up with a definition of rumor from epistemological perspectives. By understanding rumor as the ersatz of knowledge, it is possible to track the process of rumor from sprouting to dissipation. Moreover, this paper seeks to conceptualize semiotics as the joint path of multiple disciplines on studying rumor. On the one hand, semiotics helps explain the synchronic transmission of rumors as the meaning-making process of a group under social pressure as “improvised news,” which is centered on the communication process and the sociology of rumor. On the other hand, semiotics brings a powerful tool for investigating the diachronic sedimentation of social discourses as the collective memory of social groups, which constructs the uneven social sphere as institutions. This direction concerns the studies from psychoanalysis and culture studies. In this regard, a new, transdisciplinary paradigm of studying rumors is constructed yet pinned down on semiotics, both at macroscopic and microscopic levels, which welcomes more like-minded scholars to join the enterprise.