The relationship between a citizen scientist and a scientist is a bit like the relationship between a paramedic and a medical doctor. Except that the word parascientist doesn’t work, because it already has a derogatory meaning! A parascientist studies phenomena that are beyond the scope of traditional science. We don’t want citizen scientists doing that!
The key role of a paramedic is to support doctors, and to give this support in a particular context. There are not enough doctors to send one out to every place and circumstance where a doctor may be needed. Paramedics are mainly involved in doing aspects of the work of doctors in emergency situations. Paramedics don’t do everything that doctors do. They are not mini-doctors.
In the same way, citizen scientists are not mini-scientists. They do not do everything that scientists do. They assist scientists in particular areas. This assistance goes beyond invaluable. The value to science of the data which citizen scientists collect for projects such as the bird atlas, or bird ringing, is stupendously huge, in whatever currency you measure the value of scientific data.
There are some words and phrases which are genuinely descriptive. Like dining room table, or school report or olive oil.. But there are lots of very dumb expressions. Like bird book. Or walking stick. Or water bottle. Anyone can be forgiven for thinking that a fireman, or firewoman, is someone who makes fires. And that the fire brigade consists of the gang of pyromaniacs who are responsible for the really big fires.
Likewise, the term citizen scientist is pretty dumb. It goes into the same pigeonhole for crazy things as grandfather clock.
I am typing this using my laptop; I never use my laptop on my lap. My arms are too long for that to be comfortable. But we all know what a laptop is.
If aircraft followed the same pattern as olive oil, it would mean a craft consisting of air. Flying machine might be a lot better. If a soil scientist is some who studies soil, a citizen scientist ought to be a scientist who studies citizens.
In fact, there are lots of people who have given up on the term citizen scientist, and are recommending alternatives like community scientists, crowd scientists, civic science (see Wikipedia!).. But all of these have the same shortcomings as citizen scientist. The one good term would be parascientist. But, unfortunately, as we have seen above, this is a word that already has a meaning, and we cannot hijack it!
So we need to come to terms with the special definition we give to citizen scientist. We know what we mean. We just have to accept that citizen scientist is an unfortunate choice, that became embedded in the English language, in the same way as equally crazy expressions like laptop, flying saucer, and traffic jam have become everyday words that we use without thinking twice about how silly they are.

