Aspect

According to the Merriam-Webster (http://www.m-w.com/home.htm) online dictionary an aspect is an "appearance to the eye or mind". In describing an aspect you describe the part of a whole you want to emphasize.

Example:

When talking about safety procedures at your workplace, you are not saying that your work is actually about security, but you are talking about the safety aspect of your work. The safety aspect summarizes all procedures and guidelines only related to the specific topic of security and safety in your work.

---

In computer science, an aspect is part of a program that cross-cuts its core concerns, therefore violating its Separation of concerns. I.e. it is needed to complete the program, but not necessarily specific to the domain the program is written for. Isolating such aspects as logging and persistence from business logic is the aim of the aspect-oriented programming paradigm.

Another possible view is, that every major feature of the program, core concern (business logic) or cross-cutting concern[?] (additional features), is an aspect, and by weaving them together, you finally produce a whole out of the separate aspects.

The prism analogy describes aspects with terms from the domain of light. Like you split light into its many aspects (different colors) with a prism, you split a problem into its separate aspects. With another prism you can put the different colors back into a white ray of light, and by the process of weaving aspects you can put your solutions for the different aspects of a problem back into a solution for the whole problem.