A haughty person, jealous of others' gifts, interprets others, bringing his arrogant and jealous feelings into the interpretation. Then he/she sits there and figures out a way to say his scornful thought and phrase it in a way that people will take notice of what he/she is saying - and then says it. Happy is the person who doesn't do this.
Psalm 1 verse 1, says "Ashrei ha-ish asher lo halach ba'atzas rsha-im uvderech chata-im lo amad uvmoshav LEITZIM lo yashav." "Happy (praised) is the man that walked not in the counsel of the wicked, stood not in the path of the sinful, and sat not in the session of the scorners."
Pirkei Avos says that whenerver two sit together without words of Torah between them, it is nothing but a "Moshav Leitzim", s session of scorners." (Ch. 3 Mishna 2)
Tosafos Yom Tov points out that the individuals don't sit idly not studying Torah. The emphasis is they do not EXCHANGE words of Torah. Deeply involved in Torah but oblivious to one's neighbor - why not exchange a thought or ask a question? In their hearts, each deems such an exchange a waste - why? Because he scorns the aptitude of the other. Without uttering one evil word, without wasting one moment from Torah, he is labeled a "Scorner". This is all from his proud arrogant heart saturated with scorn regaring his neighbors gift of intelligence.
The letters of the word Leitz in Hebrew are Lamed Tzadik. These names of these letters mean something too. Lamed is the word for learn in Hebrew, and Tzaddik is the word for righteous. One's sense of righteousness regarding his learning makes him a "Scorner" who should be avoided by a praiseworthy person. (Panim Yafos)
"Leitz", according to Ibn Ezra, has similar letters to the word "malitz", interpreter. An interpreter transmits from one person's language to another... a scorner takes one person's secret and tells it to another.
Another hebrew word similar in letters is "Melitzah" - a polished phrase. A man who ridicules others takes pain to make his verbal attack more acceptable by polishing his repulsive idea with finely worded phrases.(Metzdas Tzion).
- adapted from the Artscroll Tehillim