I just watched a guy on YouTube who does cut testing on knives confuse 20° included with 20° per side or 40° INCLUDED. The term is included angle. The sum of the entire angle on any side of a triangle. I'm not sure what numb-skull started calling the angle "inclusive" but it's really annoying to a machinist and guy who took grade school geometry. Lifted from another website. What are your favorite pet peeves about misuse of language as it pertains to sharp stuff?