Fog, moss; from the Gaelic bog
or bhog, moist, soft.

"And so, John," said the minister, "I understand ye have gone over to the Independents?" "Deed, sir," said John, "that's true." "Oh, John," rejoined the minister, "I'm sure ye ken that a rowin' stone gathers fog." "Aye," said John, "that's true, too; but can ye tell me what gude the fog does to the stone?"

—Dean Ramsay.