Please give a detailed definition of backbiting and carrying tales and the slanderer and backbiter ("al Hamz" and "Lamz" as mentioned in Surah 104).

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Backbiting was explained by the Prophet (Peace and blessing be upon him). He said: "Do you know what Gheebah (gossip or backbiting) is?" They said, "Allah and His Messenger know best". The Prophet stated: "To say something about your brother that he does not want to be said". He was asked, "what do you think if what is said about him is true?" He responded: "If what you say about him is true, this is backbiting, and if what you say about him is not true, this is a lie. (Reported by Muslim)
Backbiting is forbidden in the light of Qur'an, Hadith and the consensus of Muslim scholars. Many scholars considered it among major sins.
Allah has drawn the most repulsive analogy to have us avoid this practice; He said: "And spy not, neither backbite one another. Would one of you like to eat the flesh of his dead brother? You would hate it (so hate backbiting." [49: 12].
Allah will give the backbiter the punishment in the Hereafter that suits his deeds committed in this world as the Prophet said: "On the night of Ascension I passed by some people who had copper nails and they were scratching their faces and their chests with them. I asked Gabriel: Who are these persons? He said, these are the people who eat the flesh of human beings and disgrace them. (Reported by Abu Dawood).
There are many other Ahadith which condemn backbiting. There are many reasons, which drive one to this bad practice. Among them are being jealous of someone, overlooking others, making jocks of them, and to try to lower their status etc. Sometime one practices it only in accordance when among bad friends.
There are two ways to get rid of this practice. One is a short while the other is a detailed one.
First, the one who indulges in backbiting should bear in mind the ugliness of this sin and the example Allah mentioned for those who commit it. He should also be reminded that on the Day of Judgement Allah takes from the good deeds of the backbiter and adds to the account of the injured person, until his rights are restored. If the backbiter has no more good deeds to cover for the injury caused by backbiting, then he will receive some of the injured persons bad deeds. It is proved in sound Ahadith.
The detailed way to stop this practice is that the one who practices it should examine the reasons for engaging in such a practice and eliminate them.
Everyone who has committed this sin should repent to Allah and ask forgiveness from him. Imam al-Bukhari related in his Sahih from Abu Hurairah that the Prophet Muhammad (Blessings and peace of Allah be upon him) said: "If any Muslim has offended his brother concerning honour or anything else, let him obtain his pardon today (in this world) before the time comes when he will have neither Dinars nor Dirhams (i.e. he will be penniless). If the aggressor may have some good deeds (in his account) the same would be deducted in equal proportion to his wrongs, if the aggressor will have no good deeds in his account, the wrongs of the aggrieved would be added to the account of the aggressor in equal proportion".
If one suspects that asking pardon from the person whom he has offended may cause more harm then good then he should talk about this person's good qualities in places and gatherings where he has talked about him badly.
According to the Islamic Sharia backbiting is permissible for religious purpose. Here are six instances where it can be permitted.
1. A report for the redress of some injustice, wrong, tyranny or high-handedness in which an oppressed person can petition the King, Qazi or person in authority, against a person who has perpetrated such offenses.
2. To seek help to stop some practice or work which may be against the principles of religion.
3. To seek a ruling (Fatwa) on a specific topic from a qualified person in authority.
4. To caution the Muslims about the evil consequences of some mischief.
5. If someone indulges in evil practices openly, for example publicly drinking liquor, treating people cruelly, causing usurpation of their property, and impositing and collecting taxes with cruelty.
6. To introduce somebody, with such nicknames like lame, deaf, blind, squint-eyed when such a person is already known by such a name. In this case, his introduction with such nicknames is permissible. But to use such words to humiliate such a person is forbidden. If he can be introduced in a more dignified way it is better to do so.
'Al-Namimah' means carrying tales for mischief. Some people repeat the words of a friend to other friend or the words of a spouse to his/her spouse to cause trouble between them. This practice is forbidden regardless of the purpose of reporting and whether the words used are true or not.
Every act, which causes breaking of relations or creates hatred between two parties is considered slander/talebearing and is forbidden.
Allah Says (interpretation of meaning): {And obey not everyone who swears much and is a liar or is worthless. A slanderer, going about with calumnies,}[68: 10-11].
The Prophet once, while passing two graves, said that, the (inmates) of these two graves are being tortured and not for any major sin, (to avoid) but in fact (he added) they are being tortured for major sins. One of them used to carry tales to make enmity among friends and the other used to urinate without any cover". (Reported by al-Bukhari).
In another Hadith the Prophet said: "Shall I not inform you of something more excellent in degree than fasting, prayer and alms giving (Sadaqah)? The people replied: Yes, Prophet of Allah! He said: It is putting things right between people, spoiling them is the shaver (destructives)". (Reported by Ibn Habban in his Sahih).
So, a Muslim should avoid this chronic disease and try to keep himself away from Hell fire and better relations with people.
"Hamz" and "Lamz" are a kind of backbiting and slandering. If one makes derogatory gestures (e.g. winking, snaking his teeth, smirking, etc.) behind a person's back such actions are called "Hamz". If he reports by his tongue then it is called "Lamz".
Imam Gazali said: 'Speaking about a person is forbidden because by doing this, one disgrades a brother in front of other persons and brings to their knowledge what the brother dislikes. The same rule applies if one indulges in the same practice by gesture, writing, indicating, or any other action, which conveys the message. Once the Prophet considered Aysha's () action backbiting in a Hadith narrated by Imam Tirmizi that she said to the Prophet: "It is enough for you in Safiyyah () that she is such and such" and she gestured with her hands, meaning that she was short. He replied", you have said a word which would change the sea if it were mixed in it.

Allah knows best.