brownfield

/B R AW1 N F IY0 L D/
noun
  1. 1

    A site, to be used for housing or commerce, that has been previously used for industry and may be contaminated or need extensive clearing

adjective
  1. 1

    Being a development that has to integrate with legacy systems.

    โ€œa brownfield projectโ€

Source: https://en.wiktionary.org/wiki/brownfield