This paper proposes a new quantitative definition for software quality. The definition is based on the Taguchi philosophy for assessing and improving the quality of manufacturing processes. The Taguchi approach, originally developed for manufacturing processes, define quality in terms of "loss imparted to society" by a product after delivery of the product to the end user. To facilitate the use of the Taguchi definition, several "loss functions" have been developed. These loss functions allow quality to be quantitatively measured in monetary values (e.g. US dollars). To illustrate the application of the Taguchi definition to a software product, examples that utilize some of the loss functions are presented. The proposed definition of software quality shows good correlation to other popular qualitative and quantitative definitions for software quality.