Literature about soft skills is extensive and you can find a lot of very interesting approaches. We propose here some "famous" definitions:

“The definition of soft skills encompasses two main categories: personal qualities and interpersonal skills. These skills are distinct from technical skills (hard skills) and include personality traits, social graces, language proficiency, personal habits, friendliness, and optimism. They are attributes that complement the technical requirements of a job. Examples of soft skills as per the definition include communication skills, critical and structured thinking, problem-solving abilities, creativity, teamwork capability, negotiating skills, time management, conflict management, cultural awareness, responsibility, etiquette, courtesy, self-esteem, sociability, integrity/honesty, empathy, work ethic, project management, and business management.” (Schulz, B., 2008. The Importance of Soft Skills: Education beyond academic knowledge. NAWA Journal of Language and Communication. Polytechnic of Namibia).

“Soft skills describe career attributes that individuals should possess, such as team skills, communication skills, ethics, time-management skills, and an appreciation for diversity‟ (Mitchell, G.W., Skinner, L.B. and White, B.J., 2010. Essential soft skills for success in the twenty-first century workforce as perceived by business educators. The Journal of Research in Business Education, 52(1), p.439).

“Academic discourse on soft skills generally refers to abilities like teamwork, collaboration, leadership, problem-solving, critical thinking, work ethic, persistence, emotional intelligence, organizational skills, creativity, interpersonal communication, and conflict resolution” (Karimi, H. S., & Piña, A. A., 2021. Strategically addressing the soft skills gap among STEM undergraduates. *Journal of Research in STEM Education*, 7(1), 21-46. https://doi.org/10.51355/jstem.2021.99).

“Soft skills are transferable skills across all disciplines. The lack of competency has implications for all stakeholders: students, employers, and educators” (Association of American Colleges and Universities, 2018; White & Shakibnia, 2019).

Despite commonalities in definitions within the literature, there is no unanimous agreement on a definitive list of soft skills. Generally, they are defined in contrast to hard skills, referring to non-technical skills that enhance professional success.

See: 

  • Heckman, J. J., & Kautz, T., 2012. Hard evidence on soft skills. Labor economics, 19(4), 451-464., 2012; 
  • Bancino, R., & Zevalkink, C. (2007). Soft Skills: The new curriculum for hard-core technical professionals. Techniques, 82(5), 20.; 
  • Andrews, J., & Higson, H., 2008. Graduate employability, ‘soft skills’ versus ‘hard’ business knowledge: A European study. Higher education in Europe, 33(4), 411-422; 
  • Sutton, N. (2002). Why can't we all just get along? Computing Canada, 16(28), 20-24; 
  • James dan James. (2004). Teaching career and technical skills in a "mini" business world. Buisness Education Forum, 59(2), 39-41; 
  • Perreault, H. (2004). Business educators can take a leadership role in character education. Business Education Forum, 59(1), 23-24).