In a December 2019 Nature article*, Grudniewicz, et al. define predatory publishing: "Predatory journals and publishers are entities that prioritize self-interest at the expense of scholarship and are characterized by false or misleading information, deviation from best editorial and publication practices, a lack of transparency, and/or the use of aggressive and indiscriminate solicitation practices.” Although this definition is from the perspective of the sciences, the definition can be seen as cross-disciplinary. You might choose to use the term predatory, exploitative, or low-quality, but these kinds of online journals are an increasing annoyance in every discipline. Be cautious and critical about unsolicited invitations from unfamiliar journals, especially those offering low-cost, quick turnaround publication schedules, and falsified editorial board memberships. Many of these journals make false or vague claims regarding inclusion on indexing and citation metrics sources such as PubMed or Scopus, or attempt to entice submissions with non-transparent author information that might at worst cause your work to be hostage to "withdrawal fees" or other threats to your author rights and ownership.
Before submitting to an unfamiliar journal, check in with your subject specialist for an objective assessment of the validity and value of the title. While there are no comprehensive lists of so-called "predatory publishers," exploitative and low quality journals have characteristics in common. Researchers can also use some of the resources linked below to investigate the integrity of potential targets before corresponding or submitting.
Authors can also use the "think, check, submit" principles to guide their decisions for publishing your book, book chapter, or journal articles:
See also: Cukier, Samantha, et al. “Checklists to Detect Potential Predatory Biomedical Journals: A Systematic Review.” BMC Medicine, vol. 18, no. 1, 2020, p. 104, doi:10.1186/s12916-020-01566-1