Words of slander
Question

If one man reviles another and says “O evildoer”, is that regarded as slander and does the hadd punishment for slander have to be carried out?.
Praise be to Allah.Firstly: 
The slander for which the hadd punishment must be carried out on the slanderer is accusation of zina (fornication or adultery) or homosexuality. In that case the slanderer must be given eighty lashes, if he does not produce four witnesses to testify to the truth of what he is saying, because Allah says (interpretation of the meaning):
“And those who accuse chaste women, and produce not four witnesses, flog them with eighty stripes”
[al-Noor 24:4]. 
Secondly: 
Words which may be used in slanderous ways are of two types: explicit or implicit. 
Explicit words are those which cannot be understood in any other way than as an accusation of zina or homosexuality, and the slanderer’s claims that he meant something other than slander cannot be accepted. 
Examples include saying “O adulterer”, “You committed zina” or “O homosexual”. 
It cannot be accepted if he says, “When I said ‘ya looti (O homosexual),’ I meant that he was a follower of the religion of Loot (peace be upon him), or that he did any of the actions of his people except that immoral action,” because this phrase, ‘ya looti’, cannot be understand in any way except as a accusation of immorality. 
As for implicit phrases, these are words that may be taken as slander or they may be understood otherwise. 
In this case the slanderer is to asked what he meant, and he has to tell the truth, because carrying out the hadd punishment on him in this world is easier to bear than punishment in the Hereafter. If he says: “I intended to slander him”, then he has slandered him, and if he says, “I meant something other than slander”, then there is no hadd punishment, but he should be given a disciplinary punishment for reviling people. 
Examples of that include saying “O evildoer” and the like. 
See al-Mughni (12/392), al-Majmoo’ (22/113), Haashiyat al-Dasooqi (6/324). 
It should be noted that reference is to be made to what words customarily mean, which varies from one country or time to another. The word may be regarded as implicit among some people and as explicit by others. So attention must be paid to that. 
Haashiyat al-Dasooqi (6/328); al-Sharh al-Mumti’ (14/289). 
Based on that, if he reviled someone and said “O evildoer”, then he should be asked what he meant by this phrase. If he says “I meant to accuse him of zina,” then this is slander. If he says, “I did not mean to accuse him of zina” then no hadd punishment is due, but he should be given a disciplinary punishment, and the judge may punish him as he sees fit, as stated above. 
And Allah knows best.