The name Cayo means Key or Cay in Spanish and is commonly used for all the islands, islets and keys in Cuba. The Jardines del Rey Archipelago, where Cayo Sabinal is located, has over 2500 keys, islets and Islands. The word Sabinal refers to the species of Juniper Sabina tree (Juniperus Sabina) that grows abundantly on the Island. The Juniperus Sabina is thought have somehow been taken to the island from Europe, either from seed cones (the cones can protect the seeds for years and also float) that floated across the Atlantic or, possibly those from a ship wreck off the coast. Juniperus Sabina is from the scale leaf species, adult leaves are mostly scale-like, similar to those of Cupressus species.
Therefore literally translated, Cayo Sabinal would mean Island of Junipers or Juniper Island.
Of course the island is also populated by the native Cuban royal palm trees, especially along the coastline beaches of Playa Bonita, Playa Los Pinos and Playa Brava.