What is the X in X-mas?
early 15c., from Middle French fertilité, from Latin fertilitatem (nominative fertilitas) "fruitfulness, fertility," from fertilis (see fertile).
fertility fer·til·i·ty (fər-tĭl'ĭ-tē)n. The state of being fertile, especially the ability to produce young.
Capable of producing offspring, seeds, or fruit.
Capable of developing into a complete organism; fertilized.
Capable of supporting plant life; favorable to the growth of crops and plants.