predominate

Something predominant stands out above all the rest. The predominant theme in an essay is the one that predominates—the main idea that the writer wants to express. (Notice the difference between the adjective and the verb; be sure not to spell the adjective with an -ate ending.) The word is widely used in many fields. For example, the predominant language of Switzerland is German; the predominant cause of obesity in children is a bad diet; and your predominant reason for wanting a larger vocabulary may be to simply be a better-educated person—though the positive effects of a large vocabulary on one's romantic life are well known.