Definition & Meaning of "smellfungus"in English

What is the origin of the term "smellfungus" and how is it used?

"Smellfungus" is a slang term for a person who is constantly complaining, critical, or sour. It comes from the 17th-century English phrase popularized by writer John Taylor, combining "smell" with "fungus" to evoke the idea of detecting rot or decay everywhere—metaphorically describing someone who always finds fault. The term is mildly derogatory and humorous, used in informal, literary, or social contexts to tease or criticize habitual grumblers. It is rarely deeply offensive and often conveys playful disapproval rather than harsh insult.