As a computer scientist, I ran into trouble recently with a piece of my game writing for a general audience, which had a few phrases like this:
For magic, each boost increments quantity.
The intention here was for "increment" to mean "adds one to", which is what it means in the technical field of computing. But I had some readers be confused by that, and I realize now that the English dictionary definition of "increment" doesn't say the same thing. E.g., the definition at dictionary.com.
Example of the feedback I received (from a fellow programmer):
I'm not sure exactly how much increments quantity means, unless Dan is
nerdily assuming people will just read that as quantity++
("quantity++" is the syntax used in a C-like language to add one to an integer quantity, called the increment operator; e.g., as in C, C#, Java, JavaScript, Go, etc… and something of an inside joke in the name of the language C++.)
Note that this question is distinguished from this related one, which asks for usage in a technical publication, and whose answer is "increment", which in my case readers have found to be unclear.
Am I overlooking any other single word in standard English which specifically means "to add one"?
Best Answer
Summarising the other answers and comments, the answer to OP's question is "No"; there is no word meaning "increase by 1" in general English.
In computer programming the verb "increment" often has that meaning, but in general it means "increase by steps". See https://www.wordhippo.com/what-is/the-verb-for/increment.html. The steps are often equal to 1, especially for counters. However the steps need not even be the same size, as in wordhippo's example
OP's example could be rephrased more clearly as