CEO
- Chief Executive Officer = directeur général
My uncle was the CEO of a large computer company.

CIA
- Central Intelligence Agency - US spy and security organization - Agence Centrale de Renseignements
The CIA was involved in the efforts to free the hostage.

C/O
- Care Of - aux bons soins de (en passant par)
I didn't know my friend's address so I sent a letter to him C/O another friend of mine.

COD
- Cash On Delivery - used when a delivery person receives cash when they deliver something
I decided to send away for some video cassettes and the company said that they would send them to me COD.

CPA
- Certified Public Accountant
The woman in our accounting department has been studying for her CPA exams for three months.

DIY
- Do-It-Yourself
I went to a DIY store and bought the materials to build a bed.

DJ
- Disc Jockey
My cousin worked in the summer as a DJ while he was going to university.

DNA
- Deoxyribonucleic Acid - main constituent of the chromosomes of all organisms
The large university has spent a lot of money in the study of DNA.

DUI
- Driving Under the Influence
The man was sent to jail for several months on a charge of DUI.