Something that's emphasized is stressed. The emphasized point of a politician's speech might be lowering taxes.
When you put stress on something or pay it extra attention, you can describe it as emphasized. There are emphasized syllables in words, emphasized subjects in school, and emphasized parts of a wedding reception speech. The source of the adjective emphasized is the noun emphasis, "importance or stress." Emphasis is a Greek word, used in rhetoric to mean "significance" or "indirect meaning," from emphainein, "let a thing be seen."