abuse

1. To cause damage or harm emotionally, physically or sexually.
The man has been charged with abusing a young girl.

2. Using something wrongly or excessively (on purpose).
He has abused drugs for over 5 years.

3. Unethical or improper use of authority by someone who has that authority.
The policeman abused his authority to take a bribe.
He was charged with abuse of power to keep prices artificially high.
The president was accused of abusing his power after ordering soldiers to shoot at protesters.