All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.
The Kuwaiti Encyclopedia of Islamic Jurisprudence defined the word aadaab (etiquette or manners) as follows, “Linguistically, the word aadaab is the plural form of adab, which denotes delicacy of manner and courtly behavior. The primary meaning of the Arabic root of adab is "to invite" or "to gather together for a banquet;" it denotes inviting people to gather around all that is good; every noble and refined characteristic, habit, or trait...”
In Islamic terminology, the word adab means refined manners; scholars allocated a chapter entitled 'Adab of the Judge,' addressing what the Muslim judge should and should not do. They also entitled chapters: 'Aadaab of Istinjaa' (cleaning oneself with water after answering the call of nature),' 'Aadaab of Prayer,' and so on. Some defined it as follows, 'Adab means putting things in their proper places.'” [End of quote]
Allaah knows best.