I have often seen leitzanus, mockery, defined along the lines of making a joke out of serious matters. Intuitively this is a good definition, but does anyone have a source which spells it out?
Some siddurs have the phrase "Ki Kel Melech Chanun V'Rachum Ata" at the conclusion of Ya'aleh v'Yavo. Some have Melech in parentheses; some don't have it at all. Can anyone tell me something about ...