The word "rigor" means strictness or extreme precision in how something is done or how rules are followed. It can also refer to the challenging nature of a task or the high level of detail and accuracy required. Full definition
Theology is not to be distinguished from philosophy by a lesser concern for rigor of thought! (religion-online.org)
It did not entirely fit with the demand for rigor when she began, and it does not entirely fit in with today's demand for that elusive brand name. (haberarts.com)
Before teachers launch a project, they often have a session with colleagues for feedback, especially on the academic rigor of the project. (edutopia.org)