Yet the word at the beginning of our portion is actually הדברים, with the leading ה, and not דברים; So why did they drop the ה when they named this portion and that of the entire book?
The reason is because the word הדברים appears also just before God began to speak the Ten Commandments (Ex. 20:1). The words that comprise the ten commandments are thus referred to as הדברים. And in order to differentiate between those words and ours of this portion, or book, they dropped the ה of the word - to yield, simply, דברים.