Define avak loshon hora and avak rechilus.
Avak loshon hora.
Literally means dust of loshon hora. A person who makes a statement that causes the listener to speak loshon hora. This is according to the Rambam and Rabbeinu Yonah (part 1 klal 9 se’ef 1 bm”c 1).
Avak loshon rechilus.
Literally means dust of rechilus. Saying someone hinted something improper about the listener, praising someone that can cause the listener to be upset with the one being praised, asking someone “Why did you do this good for Ploni?” when he refused to do you a favor, and telling someone that Ploni said he was something that people generally get upset about (for example, being old) (part 2 klal 8 se’efim 1-4).