Requisite (noun)

1. A thing that is required or necessary in a particular situation or for a particular purpose.
2. A necessary condition or requirement for something.

Origin:

Late middle english: from old french requisit, from latin requisitus, past participle of requisire "obtain by asking", from re- "again" + quaerere "to seek".

Examples:

1. Good communication skills are a requisite for success in any field.
2. Having a valid passport is a requisite for international travel.
3. Adequate funding is a requisite for the completion of any major project.
4. A basic understanding of mathematics is a requisite for most science and engineering courses.
5. Being punctual is a requisite for maintaining a professional image in the workplace.