Substance-wise, the new policy offers little improvement over the old one.

Although his speech wandered through many topics, the sum and substance of his message was a call for unity.

Researchers found traces of a perfluoroalkyl substance in the local water supply after the chemical plant leak.

Scientists detected trace amounts of a polyfluoroalkyl substance in the river sediment.

Don't take the shadow for the substance when assessing someone's character based on a few public appearances.