Holism is the idea that the whole is the parts and the parts are in the whole. What this means is that a duck's webbed feet, without the existence of water, would be meaningless. The duck is in the environment and the environment is in the duck: 'The whole is in the parts and the parts are in the whole'.
Holism is the idea that it is not the ear that hears, but ourselves. Of course we hear a Bach fugue with our ears, but if we leave what is heard only at this, with what strikes the tympanum as sound waves, then we can never hear a Bach fugue.
Holism is the study of the whole of the human condition: Past, present, and future, biology, society, language, and culture.
Holism is the notion that any individual perception is already part of an encompassing implicit understanding of the whole context.
Holism is the sense of things overall which precedes and makes possible a grasp of the relevance or the implication of specific parts.