The contention that wholes, or some wholes, are more than the sum of their parts. One special version is organicism, urging that some systems that are not literally organisms are nevertheless crucially like organisms, whose parts can only be understood in relation to their functions in the complete and ongoing whole.
(Antony Flew: A Dictionary of Philosophy, St. Martin's Press 1979)

The emphasis on the parts has been called mechanistic, reductionistic, or atomistic; the emphasis on the whole holistic, or organismic, or ecological. In twentieth-century science the holistic perspective has become known as "systemic" and the way of thinking it implies as "systems thinking". (p. 17)
...a system has come to mean an integrated whole whose essential properties arise from the relationships between its parts, and "systems thinking" the understanding of a phenomenon within the context of a larger whole. (p. 27)
According to the systems view, the essential properties of an organism, or living system, are properties of the whole, which none of the parts have. They arise from the interactions and relationships among the parts. (p. 29)
(Fritjof Capra: The Web of Life, Anchor Books 1996)

Neub. aus gr. hólon, 'Ganzes' von J.C. Smuts (Holism and evolution, 1927), eine bes. Art der Ganzheitslehre, die sich als Überwindung verschiedener einseitiger Auffassungen des Lebensgeschehens (Monismus, Pluralismus, Mechanismus, Vitalismus) versteht und Anspruch darauf macht, als "Metabiologie" an Stelle der Metaphysik treten zu können.
(J. Hoffmeister: Wörterbuch der Philosophischen Begriffe, Meiner 1955)

I use the term in a broader sense than in the traditional definitions given above. Holistic thinking is a special form of thought or view that tries to integrate all aspects and perspectives into an all-encompassing whole, not excluding, omitting or dismissing any views or concepts. On a level of fragmentary or reductionistic (analytical) thinking, certain views are irreconcilable, even completely contradictory to each other. A holistic view, however, reconciles these views in a higher synthetic view (cf. Hegel's dialectical philosophy). Furthermore, certain aspects of the universe are not intelligible or comprehensible in terms of a mechanistic-reductionistic approach, but can only be grasped holistically, that is, as a whole. Modern Chaos Theory and Complexity Theory, as well as Quantum Physics, lead science to a new way of thinking. This emerging holistic view is not new, but is idiosyncratic of the greatest philosophers and thinkers in the history of mankind.

From Greek όλος (holos = whole, entire, complete) and γέμω (gemo =to be full, contain, embrace, hold together). The holistic structure or pattern of the thought process.

A detailed study of Hologemes can be found in Essay Hologemes:

Hologemes are holistic patterns or structures of thought processes. Thoughts and particular terms or expressions of language are not identical, as analytical philosophy assumes. Although we think in terms of linguistic elements most of the time, thoughts do imply a much wider context field.
The primary idea in our mind is a complex pattern of differently connected and interconnected ideas, and this compound form is called a Hologeme. Hologemes are inexpressible and can only be understood by our mind alone.
The hologemes do not have parts, they are whole and can in their finality only understood as whole by the direct act of intuition.

The primary hologeme is the ur-thought of the Universal Mind, i.e. it is the absolute noetic unity of everything intelligible. All thoughts are ultimately synthesized within the primary hologeme. Individual Minds have a plurality of hologemes, each can be part of a next higher hologeme or consist itself of other hologemes. The Universal Mind, as the grand unificator of all individual minds, has only one original or universal hologeme that consists of an infinite number of individual or secondary hologemes (see next entry).

As opposed to the Primary or Universal Hologeme (see previous entry), individual hologemes occur as a plurality, constituting the very nature of individual minds. We think in terms of hologemes or holistic thought patterns. The different kinds and forms of hologemes being thought in our mind determine the nature of our very being, the essence of a human personality. Individual hologemes are derived from the one and original hologme. All thoughts are derived from the ur-thought, all minds are constitutive parts of the One Mind, the Universal Mind. Secondary hologemes are individual forms of thought, dependent on the structure of the Individual Mind.

From Greek ὑλη (hyle = stuff of which things are made, material, matter) and νόησις (noesis = intelligence, understanding, mind, processes of thought). The product of the symbiotic and synergetic relationship between Exohyle (Matter) and Exonoesis (Individual Mind), what is commonly called Consciousness.

From Greek ὑπο (hypo = under, below, beneath) and νόησις (noesis = intelligence, understanding, mind, processes of thought). The basic unitary reality or entity underlying and being the source of a plurality of distinct, transient and individual forms, such as those of our physical and mental world. Also referred to metaphorically as the collective, universal or cosmic Mind, the One Mind, the World-Mind.

In Essay Hyponoesis and Exonoesis I and Essay Hyponoesis and Exonoesis II, I introduce the two basic concepts of Hyponoesis and Exonoesis:

Hyponoesis is not individual but universal, and is not dependent on the brain and not bound to any material or physical property or entity. It is infinite, uncreated, without evolution, timeless, absolutely independent, supreme intelligence, the active principle in the universe, the most subtle and most powerful energy conceivable. ...
Both, mind and matter, are aspects of one substance, Hyponoesis. Hyponoesis could be conceived as an energy, from which Exonoesis and matter (and other possible substances) are derivatively created by changing the form of energy.