As attention to the nation's infrastructure becomes a matter for political discussion, there is also a focus on the word itself. The funding formula will depend upon definition, and a review of the etymology is in order. The word is traceable to NATO war mobilization studies in the 1950's and to the economic development literature of low income nations shortly thereafter. Gradually it came to be used for capital investment of all sorts—human capital as well as physical plant investment. With so diffuse a meaning, the term tended to drop into disuse. Now in the 1980's we see a revival in the use of the term, with a likely repeat of its evolution as discussion develops over resource allocation to such legitimate claimants as transportation facilities, flood control, water and sewer facilities, health, education, and other public sector responsibilities.