1. to cause someone to lose confidence, hope, or determination; to weaken the morale of
Usage: British spelling; American spelling is 'demoralize'; transitive verb
2. to corrupt the morals of; to cause moral decay in
Usage: less common; transitive verb

Examples

• The team was demoralised after losing five games in a row.
• Constant criticism can demoralise even the most confident workers.
• The soldiers were demoralised by the news of the defeat.
• She refused to be demoralised by the rejection and tried again.
• Economic hardship demoralised the entire community.
• His harsh comments demoralised the young athletes.