If you are an American speaker, you probably pronounce the word err to rhyme with air.
Although American, I went to school to nuns from Newfoundland; I learned to pronounce err to rhyme with fur, as in Pope’s verse, “To err is human; to forgive, divine.”
Literally, “to err” means “to wander or go astray from a marked path.” The noun error originally meant “the act of wandering.” Nowadays, both words are used only figuratively.
One meaning of err is “to go wrong in judgment or opinion”:
IPCC scientist and Pennsylvania State University professor of meteorology Michael Mann [said], “Many scientists felt that report erred by underplaying the degree of confidence in the linkage between climate change and certain types of severe weather…
In a religious context, “to err” means “to go astray” or “to sin”:
Affluence causes people to err from the Truth.
False teachers cause the faithful to err by their ignorance.
Err rarely occurs in everyday speech except in the idiom “to err on the side of caution”:
We cancelled a trip to California this month because of uncertainty over the safety of flying. I’d rather err on the side of caution.
I’d rather doctors erred on the side of caution than risk a fatality.
“To err on the side of caution” means, “to make the mistake of being more careful than necessary, rather than make the mistake of not taking sufficient precautions and later regretting it.”
The American pronunciation of err to rhyme with air is the source of spelling errors:
There doesn’t seem to be a true consensus on whether a UV filter is absolutely necessary for your lens. However I would rather air on the side of caution and have one.
When unsure if crossing a public boundary that may create feelings of discomfort, it is best to air on the side of caution and simply send a private message.
With rabies, ALWAYS air on the side of caution.
Another common error with err is semantic. Some speakers seem to think that “on the side of” in the expression “to err on the side of caution” means “to be on the side of,” or “to prefer” or “to show preference toward.” These speakers substitute other nouns for caution, with some interesting results:
I tend to err on the side of sports car tires v rated or higher for the best grip.
A standard television gives about 35 ftL. Big cinemas are about 15ftL. Definitely err on the side of television.
I like both [cats and dogs] but I’d err on the side of dogs.
Hide behind your money, boys. Mayor Bloomberg will always err on the side of wealth.
I’ve also seen:
err on the side of misery and guilt
err on the side of disappointment
err on the side of intelligence
Two ways to avoid errors with the verb err:
1. Always end the phrase “err on the side of” with the word caution.
2. Remember the alternative pronunciation that makes err rhyme with fur.