There are two components to creating powerful language: eliminating the words that detract from your message and adding language that, although ordinary, resonates. Great speakers use language the same way songwriters do: They use imagery to create mental pictures, repetition to make ideas stick in your mind, and rhythm to stir your emotions.
The key to power language is to recognize that words have something more than their basic meaning; they have emotional content too. And it's the emotion you're going for. Henry James said the most beautiful words in the English language were summer afternoon. Those two simple words convey a nostalgic picture to almost everyone. And the picture is universally pleasant because most people will remember one idyllic summer's day at the seashore or the ball game, rather than a sweltering journey in a crowded train or bus. The words summer afternoon simply make you feel good.
Even the sound of certain words conveys more than meaning. The word buzz not only means a whirring sound but also sounds like one. Bombastic, bamboozles, blunderbuss, nincompoop, lackadaisical, rambunctious, scalawag—all sound just like their definitions.