| Noun | 1. | Ci - a unit of radioactivity equal to the amount of a radioactive isotope that decays at the rate of 37,000,000,000 disintegrations per second Synonyms: curie |
| Adj. | 1. | ci - being one more than one hundred |
| (networking) | ci - The country code for Cote d'Ivoire (the Ivory Coast). |