noun
specification
spes-ih-fih-KAY-shun/ˌspesɪfɪˈkeɪʃn/
A precise description of required qualities or details.
The specification lists the exact dimensions required for each part.

Etymology
“Kind” and “make” combine behind the idea of constituting a particular kind, then “mentioning particularly.” Specification developed into a detailed technical description, notably an account of a device’s construction and use in patent law.
In context
so a software requirement or specification is as you said the what not the how I tell I tell you what I want the outcome that I want to achieve
More examples
- The contractor builds the cabinets to our specifications.
- Check the software specifications before buying a new computer.
- This fabric meets the specification for water resistance.
Forms
specification · specifications
specify verb — To state required details clearly and precisely.
Similar words
- requirement
- Names a condition to meet, not necessarily its detailed description.
- description
- Gives details without necessarily stating what must be provided.
- standard
- Sets a benchmark rather than describing every required detail.