Arabic text
عن أبي هريرة رضي الله عنه أن رسول الله صلى الله عليه وسلم قال: «أَتَدْرُونَ مَا الْغِيبَةُ؟»، قَالُوا: اللهُ وَرَسُولُهُ أَعْلَمُ، قَالَ: «ذِكْرُكَ أَخَاكَ بِمَا يَكْرَهُ»، قِيلَ: أَفَرَأَيْتَ إِنْ كَانَ فِي أَخِي مَا أَقُولُ؟ قَالَ: «إِنْ كَانَ فِيهِ مَا تَقُولُ فَقَدِ اغْتَبْتَهُ، وَإِنْ لَمْ يَكُنْ فِيهِ فَقَدْ بَهَتَّهُ».
Translation
Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said: "Do you know what backbiting is?" They said: "Allah and His Messenger know best." He said: "It is to say of your brother what he dislikes." It was said: "What do you think if what I say of my brother is true?" He said: "If what you say of him is true, you have backbitten him; and if not, you have slandered him."
Explanation
The Prophet (may Allah's peace and blessings be upon him) clarified the prohibited backbiting, which is to speak about an absent Muslim in a way he dislikes, whether you mention traits related to his manners or appearance, like saying the one-eyed man, the cheater, the liar, and or any other reprehensible trait, even if it truly exists in him. However, if the trait does not exist in him, this is worse than backbiting. This is slander, which is to fabricate bad things about someone.
Source: HadeethEnc.com