This verb means showing a wrong idea about something, often by acting or looking different. It is used when what you see or think is not the true fact.
Her calm face belied her fear inside.
His smile belied his real anger.
This is used when someone or something does not show their real quality or feeling, giving a wrong idea about them.
The cheerful tone belied the bad news.
Her loud voice belied her small size.
Here, belie means something hides the true facts or feelings so others don’t see the real truth.
The bright colors belied the poison inside.
The smile belied her sadness.