Definitions:

1. Abbreviation for Celsius or centigrade. NOUN
   • Heat the oven to 180 degrees C.
2. In music, C represents the first note in the C major scale. NOUN
   • He played a song in the key of C.
3. the 3rd letter of the Roman alphabet noun
   • 'Charlie' can be used as a phonetic for the letter c.
4. The Roman numeral for 100. adjective
   • The year C can also be written as 100.
5. the speed at which light travels in a vacuum noun
   • The constancy and universality of c is recognized by defining it to be exactly 299,792,458 meters per second.
6. The third highest class of academic grades; it indicated that your work was average. NOUN
   • The teacher assigned a grade of C for the group project.

Synonyms:

• hundred
• light speed
• speed of light