Definition of "moat"
noun:
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A deep, wide defensive ditch, normally filled with water, surrounding a fortified habitation.
from Wiktionary, Creative Commons Attribution/Share-Alike License -
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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
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