Guṇa (Sanskrit: गुण) depending on the context means 'string, thread or strand', or 'virtue, merit, excellence', or 'quality, peculiarity, attribute, property'.
The concept originated in Samkhya philosophy, but is now a key concept in various schools of Hindu philosophy. There are three gunas, according to this worldview, that have always been and continue to be present in all things and beings in the world. These three gunas are called: sattva (goodness, constructive, harmonious), rajas (passion, active, confused), and tamas (darkness, destructive, chaotic). All of these three gunas are present in everyone and everything, it is the proportion that is different, according to Hindu worldview. The interplay of these gunas defines the character of someone or something, of nature and determines the progress of life.
In some contexts, it may mean 'a subdivision, species, kind, quality', or an operational principle or tendency of something or someone. In human behavior studies, Guna means personality, innate nature and psychological attributes of an individual.
There is no single word English language translation for the concept guna. The usual, but approximate translation is "quality".
Guna appears in many ancient and medieval era Indian texts. Depending on the context, it means:
Guṇa is both a root and a word in Sanskrit language. Its different context-driven meanings are derived from either the root or the word. In verse VI.36 of Nirukta by Yāska, a 1st millennium BC text on Sanskrit grammar and language that preceded Panini, Guṇa is declared to be derived from another root Gaṇa, which means "to count, enumerate". This meaning has led to its use in speciation, subdivision, classification of anything by peculiarity, attribute or property. This meaning has also led to its use with prefixes such as Dviguna (twofold), Triguna (threefold) and so on.