The term Limnosystem is underused term and it suffers from an insufficiently sound conceptual framework of conceptualization. It is too often reduced to the ecosystem approach concerning a lake or to an approach taking in the connections between a lake and its basin. The potential richness of the concept is discussed from the epistemology of other existing terms: the lentic ecosystem favouring biocenosis, the fluvial system favouring biotope, the geosystem inspiring modelling, the hydrosystem created for the river basin. This leads to reconsideration of the spatio-temporal scales in the light of thinking on the closed ecosystem, lake microcosm and endemism, and on the open hydrosystem, up to now looking at tributaries rather than outlets. An attempt is made to frame the classical components of the geosystem, its structure, functioning and behaviour, within the processes of limnological geography which differentiates lakes from ponds and rural pools, searches for discontinuities within water bodies, comparing the relative influences of major processes in stagnant water (forced convection in lakes and great reservoirs, free convection in ponds) and those of the temporal rhythms of mixing (oligo-, di- or mono-mixis in lakes, discontinuous polymixis in ponds, continuous polymixis in pools). Finally, the place of society is discussed, highlighting the mishandling of artificial water bodies in ecosystemor even hydrosystem-based approaches. The concept of limnic anthroposystem would probably be suitable for resolving this problem. A new definition of the limnosystem is finally suggested.