Webster's Revised Unabridged Dictionary · 1913

Demoralize

Demoralize , transitive verb

[French démoraliser; pref. dé- (Latin dis- or de) + moraliser. See Moralize.]

To corrupt or undermine in morals; to destroy or lessen the effect of moral principles on; to render corrupt or untrustworthy in morals, in discipline, in courage, spirit, etc.; to weaken in spirit or efficiency.
The demoralizing example of profligate power and prosperous crime. — Walsh
The vices of the nobility had demoralized the army. — Bancroft