Colours: aḥmar and ḥamrāʾ

Six basic colours follow their own pattern. The masculine looks like أفعل, and the feminine is a different-looking word on the pattern فعلاء:

• أحمر → حمراء (red)
• أزرق → زرقاء (blue)
• أخضر → خضراء (green)
• أصفر → صفراء (yellow)
• أبيض → بيضاء (white)
• أسود → سوداء (black)

Never add ة to these colours: السيارة حمراء (the car is red). After a definite noun the colour takes ال too: السيارة الحمراء (the red car). Many names are built this way: البحر الأحمر (the Red Sea), الدار البيضاء (Casablanca). Other colours are nisba adjectives and simply add ة: بني → بنية (brown), رمادي → رمادية (grey), برتقالي، وردي (orange, pink).