Merriam-Webster's Definition of the noun slander:
"the utterance of false charges or misrepresentations which defame and damage another's reputation"
This behavior to defame another person by false or lying statements has always been wrong.
In the Holy Bible Old Testament, given by God through Moses, were ten commandments that were written in stone and contained as the ninth commandment this, "You shall not bear false witness against your neighbor." Exodus 20:16 NASB. If they violated this commandment, they sinned.
This type of behavior is a very serious offense. The Old Testament law given by Moses had more instruction related to this offense.
15 "A single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed.
16 "If a malicious witness rises up against a man to accuse him of wrongdoing,
17 then both the men who have the dispute shall stand before the Lord, before the priests and the judges who will be in office in those days.
18 "And the judges shall investigate thoroughly; and if the witness is a false witness and he has accused his brother falsely,
19 then you shall do to him just as he had intended to do to his brother. Thus you shall purge the evil from among you.
20 And the rest will hear and be afraid, and will never again do such an evil thing among you." Deuteronomy 19:15-20 NASB.
These particular laws are good for any land or country. Any country, kingdom, or sovereign nation that revels in the fact that they do not have these or do not enforce them, do so to their own moral destruction and degradation.
Today, through the New Testament in the Holy Bible, the law against slander is given to the people of God who are citizens of His kingdom. The people who are citizens of this kingdom are called Christians and since the ultimate commandment of God given to His people is to love (agape) one another, those who are Christian are therefore commanded to do no harm to a neighbor. So, as a result he will not slander his neighbor; otherwise he is not behaving as a true Christian.
Nevertheless, the New Testament words are written as follows:
8 "But now you also, put them all aside: anger, wrath, malice, slander, and abusive speech from your mouth.
9 Do not lie to one another, since you laid aside the old self with its evil practices,
10 and have put on the new self who is being renewed to a true knowledge according to the image of the One who created him . . ." Colossians 3:8-10 NASB.
"And beyond all these things put on love, which is the perfect bond of unity." Colossians 3:14 NASB.
Anyone claiming to be Christian and not willing to practice these teachings will not be saved in the end. Don't take my word for it, read what the word of God says on it:
"Or do you not know that the unrighteous shall not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, shall inherit the kingdom of God." 1 Corinthians 6:9-10 NASB.
The word reviler is a more general term used for those using abusive speech. Hence, slanderers being more specific are included in this term and they will not inherit the kingdom of God in heaven.
Love (agape) is the answer and behavior that we must practice.
"Love does no wrong to a neighbor; love therefore is the fulfillment of the law." Romans 13:10 NASB.