preposition a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause
Used in phrases like 'turn on' or 'click on' to indicate activation or selection
Used in phrases like 'on the agenda' or 'on the market' to indicate relevance or availability
Used in phrases like 'on the field' or 'on the court' to indicate location or participation
Used in phrases like 'on the road' or 'on the track' to indicate location or direction
Used as a preposition to indicate location or position
The writer was on deadline to submit the article by the end of the day.
The psychologist was on call for emergency consultations over the weekend.
The doctor was on duty at the hospital for a 24-hour shift.
The lawyer was on retainer for the high-profile case.
The engineer was on site to oversee the construction project.