Infrastructure is a term that is defined in different ways. The Oxford English Dictionary notes that originally it was meant to describe military roads and structures like bridges. The word was imported from French, where it describes a subgrade, the original material underneath pavement or a railway bed. It comes from a combination of the Latin prefix “infra”, meaning “below” and “structure”.
From the Concise Dictionary of English: The basic facilities, services, and installations needed for the functioning of a community or society, such as transportation and communications systems, water and power lines, and public institutions including schools, post offices, and prisons.