• 観客かんきゃく — audience, spectators
• 乗客じょうきゃく — passenger
• 客室きゃくしつ — guest room
• 客船きゃくせん — passenger ship
• 客観的きゃっかんてき — objectively
• 客車きゃくしゃ — passenger car (train)

客 is made of 宀 (roof) and 各 (each), symbolizing someone who comes under a roof — a guest or visitor. Over time, it has come to mean anyone who visits, stays, or uses a service, including travelers and customers.