Point symmetry is essentially a discrete concept, whereas molecular structures and their conformational changes display continuous features, even within semi-classical models. Using the formalism of fuzzy-set theory, we propose a continuous extension of the point-symmetry concept for quasi-symmetric structures. For each pointkof the reduced nuclear configuration (metric) spaceMof the set of all molecular systems having a specified stoichiometry, and for an energy criterion ϵ suggested by the statics or the dynamics of the systems, we define membership functions μi(k, ϵ) which generate fuzzy subsetsSi(ϵ) of the metric spaceM. These fuzzy subsets are used to obtain a continuous extension of the symmetry point groups of formal, classical, nuclear configurations.