cd

Everyday

1. A CD (compact disc) is a thin, shiny, round plastic disc that stores music or computer data, read by a laser. tree →
2. (computing) «cd» is a command for «change directory»: it moves you to another folder in a terminal. tree →
3. (science) «cd» is the symbol for the candela, the unit of light brightness. tree →
4. Other meanings in context: CD can mean «certificate of deposit» (money) or «corps diplomatique» (diplomat's car sign). tree →

In the lessons

In everyday life CDs were used for music and games before streaming; many families still have them. In computing and coding lessons, «cd» is one of the first terminal commands. In history of technology, the CD followed records and cassettes. Phrases: «burn a CD», «CD player».

Examples

• Grandad still listens to music on CDs. tree →
• Put the CD in the player and press play. tree →
• The CD was scratched, so it kept skipping. tree →
• Type «cd Documents» to go into the Documents folder. tree →
• Our class made a CD of our songs. tree →
• A CD is read by a laser beam. tree →

Note

Usually capitals: CD; plural CDs (no apostrophe). Say each letter: «see-dee». In computing it is small letters: cd. «Disc» with a c is used for CDs and DVDs.