Serena comes from the Latin serenus, meaning "clear" or "tranquil" — referring originally to the sky. The English "serene" derives from the same root. The name has been used since ancient Rome.
Serena Williams (born 1981), considered the greatest women's tennis player of all time with 23 Grand Slam singles titles, gave the name its modern global resonance. Today Serena sits in the U.S. top 250.
Serena reduces to nine — the number of calm strength.