1. in a deep or complete way
Usage: often used with sleep
2. in a thorough or complete manner
3. in a sensible or logical way

Examples

• She slept soundly through the thunderstorm.
• The baby was sleeping soundly in his crib.
• The team was soundly defeated in the championship game.
• His argument was soundly reasoned and well-supported.
• The house was soundly built to withstand earthquakes.
• The critics soundly rejected the proposal.
• He was soundly beaten in the chess match.