verb (used with object), em·pha·sized, em·pha·siz·ing. to give emphasis to; lay stress upon; stress: to emphasize a point; to emphasize the eyes with mascara.

Is emphasize on correct?

You can place emphasis on something, or you can emphasize it, but you can't emphasize on it or stress on it, though you can place stress on it.

Is there such a word as emphasis?

special stress laid upon, or importance attached to, anything: The president's statement gave emphasis to the budgetary crisis. something that is given great stress or importance: Morality was the emphasis of his speech. Rhetoric. special and significant stress of voice laid on particular words or syllables.