moat

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

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

No matter how good your company's product is or how quickly the industry is growing, if there is no moat, competitors will invade your castle and burn it down.

“I think ‘moats’ are lame,” Mr. Musk had said during a Tesla earnings call. It was a criticism of an economic principle that Mr. Buffett had coined in 1999 and that has become something of a mantra for his faithful: Invest in businesses “that have wide, sustainable moats around them.”

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

A clear ring outside the eyewall of a tropical cyclone.

A hill or mound.

To surround with a moat.

A surname.