When people want to categorize their content, they don't think to themselves, "I want to add a system of taxonomy to my website", they think "how do I add categories?". We need to make our user-interfaces match the mental model of these users.
I propose that we change the word "Taxonomy" in the user interface to "Categories" everywhere it appears. I believe this was what it said back in Drupal 5 (or was it 4.7) and people had a much easier time with it back then.
Also up for debate: Is it worth renaming "Vocabularies" and "Terms" or would that do more harm than good?
Brainstorming of Issues 1. Taxonomy A. English speakers do not regularly use or understand the word "taxonomy"; it should be avoided wherever possible in Drupal. B. "Taxonomy" is largely equivalent to: classification, ontology [yes, a word even worse than "taxonomy"], categorization, organization, etc. 2. Vocabulary A. English speakers do not regularly use or understand the word "vocabulary" in any sense other than one's use of words in a given language; it should be avoided wherever possible in Drupal. B. "Vocabulary" is largely equivalent to: category, order, group, set, division, class, structure, cluster, hierarchy, tree, graph, network, etc. 3. Term A. "Term" isn't terrible but is also used rarely in English; when it is used, "term" frequently signifies time rather than an element. B. "Term" is largely equivalent to: tag, label, node [this goes to show how undistinctive, i.e. useless, "node" is], mnemonic, key, keyword, element, item, designation, etc.
Principles of Assessment 1. What is most intuitive to the beginning user? 2. Intermediate and expert users will adapt to any terminology that labels a set of features and is sufficiently described or discoverable, but for beginners the terminology is very important to the learning curve. 3. Don't worry about the exact definitions for any particular word: worry about perception, first impressions, and standard practice.
Let's Look to History (aka, there is nothing new under the sun) - Initial creation of taxonomy.module (Apr. 2002) - Should we rename "taxnomy" to "classification"? (Jun. 2003) - Renamed 'taxonomy' menu to 'categories' for sake of usability. (Apr. 2004) - Drupal terminology suggestions (Feb. 2006) - Taxonomy module terminology (Feb. 2006)