"Decepticon" basically translates as "You are being deceived" - Megatron's call to arms.

"Decepticon" itself is obviously an invented word that comes from 'deception.' But 'deception' comes from the Old French word decepcion, which looks and sounds more like "Decepticon." And "decepcion" comes from the Latin word dēcipiō ("to mislead").

For those who may not know, Latin words transform in order to denote variations in meaning. We call these different modes "declensions." Dēcipiō is the Third Conjugation of the word "dēceptus" (deceived, cheated). But of course, Megatron isn't saying that people have been deceived, he's saying that they are being deceived, and for this we need to look at the second-person plural present passive imperative form of dēcipiō, which is DECIPIMINI. Translation: "You are being deceived."

Now I'm under no illusion that Bob Budiansky had any of this in mind when he made the word "Decepticon" back in 1984. They're deceptive Evil Decepticons(TM), boo! And obviously "Autobot" was simply a portmanteau of "automobile" and "robot" (since all the first year Autobots were automobiles), but of course in the IDW universe it initially was a shortening of "automaton robots," then "autonomous robots." But I think it is cool that current continuity has given these names far greater depth in their meaning than initially intended.