Holism (from Ancient Greek ὅλος (hólos) 'all, whole, entire', and -ism) is the idea that various systems (e.g. physical, biological, social) should be viewed as wholes, not merely as a collection of parts. The term "holism" was coined by Jan Smuts in his 1926 book Holism and Evolution.
The exact meaning of "holism" depends on context. Smuts originally used "holism" to refer to the tendency in nature to produce wholes from the ordered grouping of unit structures. However, in common usage, "holism" usually refers to the idea that a whole is greater than the sum of its parts. In this sense, "holism" may also be spelled "wholism" (although the two are not etymologically related), and it may be contrasted with reductionism or atomism.
The term holistic when applied to diet refers to an intuitive approach to food, eating, or lifestyle. One example is in the context of holistic nursing, where "holism" refers to assessment of a person's health, including psychological and societal factors, rather than only their physical conditions or symptoms. In this sense, holism may also be called "holiatry." Some religious institutions practice a holistic dietary and health approach, such as Hinduism and the Seventh-day Adventist Church.
In philosophy of science, logical holism is the concept that a theory can only be understood in its entirety.
Michael Esfeld has suggested that holism is opposed to analytic philosophy, "holism with respect to intentional phenomena is widespread among analytic philosophers".