What is the X in X-mas?
1560s, "to cause to multiply," from Latin propagatus, past participle of propagare "to set forward, extend, procreate" (see propagation). Intransitive sense "reproduce one's kind" is from c.1600. Related: Propagated; propagating.
propagate prop·a·gate (prŏp'ə-gāt')
v. prop·a·gat·ed, prop·a·gat·ing, prop·a·gates
To cause an organism to multiply or breed.
To breed offspring.
To transmit characteristics from one generation to another.
To cause to move in some direction or through a medium, such as a wave or a nerve impulse.