Serena and Venus Williams are two of the most successful professional tennis players in history. They are sisters, and Serena is the older of the two. The crossword solutions for the term SERENA, TO VENUS are SIS (3 letters) and KIDSISTER (9 letters). SIS is an abbreviation for sister, and KIDSISTER is a combination of the words kid and sister, referring to the fact that Serena is the older sister of Venus.