Example : The requirements of his work affected his health.
There were many demands on his time.

Synonyms : demand

Example : Food and shelter are necessities of life.
The essentials of the good life.
Allow farmers to buy their requirements under favorable conditions.
A place where the requisites of water fuel and fodder can be obtained.

Synonyms : essential, necessary, necessity, requisite

Example : Latin was a prerequisite for admission.

Synonyms : prerequisite