This is the 5873rd most frequent French word.
cyril
"Cyril" is a proper noun in French, typically a masculine given name.
Here, 'Cyril' is used as a proper noun, specifically as the name of an individual.
Cyril est mon ami depuis longtemps.
Cyril has been my friend for a long time.
In this sentence, 'Cyril' again serves as a proper noun, referred to within the possessive context of something created by him.
Le livre écrit par Cyril est fascinant.
The book written by Cyril is fascinating.
'Cyril' operates as a proper noun, being the entity with whom the speaker interacted.