rain man meaning (derogatory): definition

rain man

noun

Etymology From the 1988 film Rain Man, about an autistic man with the name Raymond, misinterpreted as “Rain man” by his brother in childhood.

Derogatory An autistic, or mentally and/or socially impaired person.

Derogatory A non-autistic or impaired person whose mannerisms are similar to such people.

Humorous An expert at something.

Lovingly dubbed the Rain Man of Weed by her family, Heylia James is legendary in West Adams for being able to "eyeball an ounce from outer space with her glasses cracked," and for making "everybody's business my business" ("You Can't Miss the Bear").2007, Kera Bolonik, In the Weeds, →ISBN, page 114:
David Milarch calls him the “rain man of trees” because of his brilliance with tree data and his uncanny knack for finding the big ones.2013, Jim Robbins, The Man Who Plants Trees, →ISBN:

1 more example

The mentorships were plenty, starting with Brian Derdall, a sort of rain-man genius in Engineering, along with T-man the technology guru, new hire peers Alex and Joel, and my new senior co-workers Ivan, Robert, and a sort of management mentor John.2013, Mike Doiron, Thread of Life: An Adoption Story, →ISBN, page 74:

noun

Etymology From rain + man.

A man who is believed to have power to control the rain.

The special relation between men and their totems is shown by a belief which exists in a large number of tribes, to the effect that the men have the power to make their own totem animal or plant increase in numbers; so that a kangaroo man can cause the kangaroos to multiply, a rain man can make rain, and so on. A kangaroo man cannot make rain, nor can a rain man do anything to increase the number of kangaroos.1913, Walter Hutchinson, Customs of the World, →ISBN:
We believe that if we want rain, the rain man of the tribe must imitate the rain by squirting water from his mouth, and the painters must retrace the age-old paintings at the cave of the water totem.1978, William Tydeman, The Theatre in the Middle Ages, →ISBN:

2 more examples

As a huge crowd watched in anticipation, the 52-year-old rain man whooped and chanted while hopping about on a hillside.1995 November 7, Mike Foster, “Raindancer charged with manslaughter - after 7 die in flooding!”, in Weekly World News:
This is presumably because CIFOR used the services of a “rain man,” whose charges to keep rain away from Bogor for the evening were a small fraction of what it would have cost to hire a marquee.2005, Nathan C. Russell, Simone Staiger-Rivas, Knowledge-sharing solutions for a CGIAR without boundaries, →ISBN, page 15:

A spirit of the rain.

These depict in vivid descriptions how the rain man in the west expands in the form of a black cloud; white clouds precede him which unfold like a flower;2009, Andrea Bandhauer, Maria Veber, Migration and Cultural Contact: Germany and Australia, →ISBN, page 71:
In Santiago Atidán some saints' images are the embodiments of ancestral protective spirits called naguales — community founders, lightning men, mist men, rain men, earthquake men — who retreated to the mountains leaving the images and sacred bundles behind.2010, Garrett W. Cook, Renewing the Maya World: Expressive Culture in a Highland Town, →ISBN: