He used a solecist phrase in his speech.

The solecurtids are small marine creatures found in rocky tide pools.

I found a solecurtid on the beach.

The soleid is a type of flatfish found in coastal waters.

The soleids are a family of fish found in freshwater rivers and lakes.

The atmosphere in the cathedral became solemner as the ceremony progressed.

He walked around in his soleless shoes.

This is the solemnest occasion of the year.

He is solecising in his speech.

He solecises frequently in his speeches.