Are chilies technically peppers?
Chili is a common reference to chili peppers in an abundance of countries, but they fall within the same designation as other so-called "peppers" such as bell pepper, cayenne, jalapeno, etc. because they are all of the same genus Capsicum. They differ, however, from traditional real peppers (black pepper for example) of the Piperaceae family. Capsicum actually belongs to the nightshade family (Solanaceae), but so do potatoes.

The word pepper originates from a south Indian term for the long pepper plant which was used as spice at the time and is a member of the Piperaceae family. I think that people have generalized chili as a pepper in this case due to the heat component, but this section of the answer is also off topic for this site.