tranquillizer or tranquilliser(NAmer tranquilizer) noun

• comprise
• compromise
• compromising
• comptroller
• compulsion
• compulsive
• compulsory
• compulsory purchase
• compunction
• compurgation
• compurgator
• computation
• compute
• computer
• computer-aided design
• computerate
• computer dating
• computer game
• computerize
• computer language
• computer-literate
• computer science
• comrade
• Comsat
• Con