Continual should not be confused with continuous. Continual means "frequently repeated." Continuous means "uninterrupted."

Convene, which means "to come together," should not be confused with convoke which means "to bring or call together." A legislature convenes. It cannot be convened by another, but it can be convoked.

Crime is often used for offenses against the speaker's sense of right. Properly crime is a technical word meaning "offenses against law." A most innocent action may be a crime if it is contrary to a statute. The most sinful, cruel, or dishonest action is no crime unless prohibited by a statute.

Dangerous should not be used for dangerously ill.

Data is plural.

Deadly, "that which inflicts death" should not be confused with deathly, "that which resembles death."

Decided must not be confused with decisive. A decided victory is a clear and unmistakable victory. A decisive victory is one which decides the outcome of a war or of a campaign.

Decimate means to take away one-tenth. It is not properly used in a general way of the infliction of severe losses.

Definite which means "well defined" should not be confused with definitive which means "final."

Demean is related to demeanor and means "behave." It should be carefully distinguished from degrade or lower.