What type of effects does the term "insidious" generally refer to?

The term "insidious" refers to something that develops gradually and often stealthily, while usually leading to harmful consequences. This means that the effects are not immediately apparent, making it particularly dangerous. In contexts such as health, psychology, or even behavior, insidious issues can creep in unnoticed, causing deterioration over time before the harm becomes evident.

For example, insidious diseases can progress without noticeable symptoms until they reach an advanced stage, making treatment more challenging. Similarly, insidious behaviors can erode relationships or organizational integrity while going unnoticed at first. This gradual nature of harm is what sets "insidious" apart from terms that may describe immediate or obvious effects, which is why this understanding of the term directly aligns with the answer choice provided.