This "special dress" is more commonly known as the "habit" or "religious garb." Religious wear the habit as a witness to all who see them, that their life is set apart in a special way for God. The traditional habit is a sign of their consecration, and also a witness of poverty and simplicity of life.
You could also identify a community by the habit they wear. Each religious institute has its own habit with a distinct pattern, color, and meaning, although some religious communities do not wear habits.
The religious habit is received upon entering the Novitiate. The habit consists of a black dress, gray scapular, braided belt, crucifix, wooden cross, a veil, and black shoes or sandals.
For a Disciple of the Lord Jesus Christ the black habit symbolizes repentance, renunciation of the vanities of this world, and her desire to live only for God.
The scapular reminds her that she has freely chosen a "yoke of obedience," and the veil is a sign of her submission to the Lord under those He has placed over her as her Superiors.
The Novice's white veil means she is a learner in the "school of perfection." At her first profession of vows she receives a gray veil and at final profession, a blue band is added to this veil as a sign of her consecration to the Immaculate Heart of Mary. The blue color is indicative of her love and devotion to Mary, her mother.
The wooden cross that she wears in her belt reminds her of Jesus' words, "If any man wishes to follow me, let him deny himself, take up his cross, and follow in my footsteps." (Mt. 16:24)
She makes her own belt, braiding three sets of cord strands together. The first set represents herself ÷ body, soul, and spirit. The second, her neighbor ÷ their body, soul, and spirit. The third one, the Holy Trinity ÷ Father, Son, and Holy Spirit. Weaving these three sets of braided strands together represents the Body of Christ. We call it the belt of unity as a reminder that we belong to the one mystical Body of Christ.
Even our shoes or sandals remind us to eagerly spread the gospel of our Lord Jesus Christ with zeal!
Because the essence of Religious Life lies on our bridal relationship with our Lord Jesus Christ, we wear a ring that we receive at perpetual profession; a symbol of God's fidelity to us and ours to Him.
Wearing a traditional habit serves as a witness to point people to God and as a daily reminder to the Sister who has given up all to follow in the footsteps of Jesus more closely.