**Background:** I have been searching for succinct language for referring to how "advanced" a topic or skill might be. I've found things like [Integrative Complexity][1] and the [Model of Hierarchical Complexity][2], which seems to describe a school of thought, but falls short of providing consistent language for comparing examples within that school of thought. By "advanced", I am intending to communicate a greater amount of pre-requisite knowledge and/or a higher degree of complexity. I toyed around with some terminology such as "Depth of Knowledge Required" at first, but it seemed lacking to me for some reason. **Question:** Is there a published set of language one could refer to in order to describe the concept of how advanced/complex a particular topic or skill is? **Edit:** An example application where this terminology would be helpful could be in determining what the appropriate course of action would be to introduce a concept/topic to another person. For clarification, how would I compare the following two examples: *Computational Genomics* in general might require additional knowledge compared to *biological taxonomy* *Non-linear dynamics* involves many more pre-requisites than does *algebra*. It's not that either option can't be complex or involve high level work, but to engage with the topic *for the first time* one clearly would be more difficult to approach than the other. [1]: https://en.wikipedia.org/wiki/Integrative_complexity [2]: https://en.wikipedia.org/wiki/Model_of_hierarchical_complexity