As someone learning about Amateur Radio, you’ll hear the term “Elmer” and “Elmering” a lot! A ham radio “Elmer” is someone who personally guides
and tutors a new ham, both before and after earning a license.
It doesn’t refer to anyone in particular, just the more experienced hams who help newcomers.
Using the word “Elmer” to mean “mentor” is unique to ham radio. Rick Lindquist, WW1ME traces the origin of the term to the March 1971 issue of QST magazine; the term appeared in a “How’s DX” column by Rod Newkirk, W9BRD. Rod’s mentor was a ham named Elmer and Rod thought every new ham should have an Elmer of their own. The name stuck and since then, “Elmering” has meant “helping.”
Every ham has at least one Elmer at some point. You will, too, and if someone refers to you as their “Elmer,” you can be proud.
Source: Ham Radio License Manual, 4th edition