Two centuries ago, some Americans believed that an anti-fogmatic, a dose of spirituous liquor, would relieve the unhealthy effects of damp and rain. A dram before breakfast was said to counteract the figurative or literal fog of the early day, hence its name. It was even supposedly recommended by physicians:

Its great utility in preserving the planters from the effects of the damp and unwholsome air of the morning, has given it the medical name of an Antifogmatick.

[The Massachusetts Spy, or the Worcester Gazette, 12 Nov. 1789]