adjective Reserved is used as an adjective to describe someone who is quiet, shy, or restrained in their behavior or communication.
Reserved seats on a flight or train
Reserved seating for VIP guests
Reserved tickets for a concert or show
A reserved table for a special occasion
Reserved room for a guest
In the literary world, a reserved writer may be someone who is more introverted and prefers to work alone rather than in a group setting.
A reserved psychologist may be someone who is more observant and listens more than they speak during therapy sessions.