Wikipedia
Styāna
Styāna (Sanskrit; Tibetan phonetic: mukpa) is a Buddhist term that is translated as "lethargy", "gloominess", etc. In the Mahayana tradition, styāna is defined as a mental factor that causes the mind to be withdrawn, unclear, and unable to focus.
Styāna is identified as one of the twenty secondary unwholesome factors within the Mahayana Abhidharma teachings