Sexual harassment refers to any unwelcome sexual advance or conduct on the job that creates an intimidating or offensive working environment. It is an unsolicited, offensive behavior that inappropriately asserts sexuality over another person, the behavior may be verbal or nonverbal.
Other /More definition:
Sexual Harassment refers to any unwelcome sexual advance or conduct that usually happens on the job or in a workplace that creates an intimidating or offensive working environment.

Moreover, Sexual harassment maybe defined as:

1. The subjection of individuals to unwelcome sexually oriented behavior.

2. Unwanted sexual attention from someone in school or in the workplace and also includes unwelcome sexual jokes, glances, or comments, or the use of status or power to coerce or attempt to coerce a person into having sex.

3. unwelcome verbal or physical conduct of a sexual nature.

4. Unwanted and uninvited sexual contact or harassment of a person usually those with a higher position in a workplace to another emloyee who is usually a subordinate; or in a school setting - a teacher harassing a student often those who wants to pass a subject.
List of books: Sexual,harassment