gradually and increasingly causing harm
insidious - sly
Something ‘insidious’ is unpleasant and dangerous and develops in a slow, gradual way so that it is not easily noticeable. For that reason, it is often associated with something sly, unobvious, and corrupting, like a disease or a plot. More commonly used in a professional context.
The doctor explained that stress can be quite insidious, and leads to long term problems if ignored.
That company’s mission statement is insidiously misleading. They use it to conceal their true intentions.
While the obvious results of the problem are being addressed, I’m worried that the more insidious aspects are being overlooked.