1. to make something flat or flatter; to press down or compress
2. to knock down or defeat decisively
Usage: informal
3. to lower in pitch or tone; to make less sharp or prominent
Usage: music

Examples

• She flattens the dough with a rolling pin to make cookies.
• The boxer flattens his opponent with a powerful punch.
• The heavy rain flattens the grass in the yard.
• He flattens the cardboard boxes before recycling them.
• The musician flattens the note to match the key.
• The storm flattens entire forests in its path.
• She flattens her hair with a straightener every morning.