moat

/mษ™สŠt/
noun
  1. 1

    A deep, wide defensive ditch, normally filled with water, surrounding a fortified habitation.

  2. 2

    An aspect of a business which makes it more "defensible" from competitors, either because of the nature of its products, services, franchise or other reason.

  3. 3

    A circular lowland between a resurgent dome and the walls of the caldera surrounding it.

  4. 4

    A hill or mound.

Synonyms

verb
  1. 1

    To surround with a moat.

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