nodding acquaintance, a

a nodding acquaintance

A very limited knowledge of or familiarity with a given person or thing. I'll help you as best I can, but I only have a nodding acquaintance with property laws. I have a nodding acquaintance with him, but I wouldn't feel comfortable asking him to help me on this project.
See also: acquaintance, nod
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

nodding acquaintance

Superficial knowledge of someone or something, as in I have a nodding acquaintance with the company president, or She has a nodding acquaintance with that software program. This expression alludes to knowing someone just well enough to nod or bow upon meeting him or her. "Early 1800s]
See also: acquaintance, nod
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

nodding acquaintance, a

Superficial knowledge. An early nineteenth-century term, it conjures up the era when the formal bow was a normal greeting. Thomas Hughes used it in Tom Brown at Oxford (1861): “Many with whom he had scarcely a nodding acquaintance.”
See also: nod
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
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