When I highlight on a word and click on ‘look up…’ it comes up with the Dictionary definition and sometimes a Thesaurus for the word comes up. However, sometimes, if you scroll, the Wikipedia definition comes up, which makes me skeptical of the computer’s sources. Wikipedia can be edited by anyone, which does not make it a reliable source. It comes in handy when you need a quick definition of something, but it should not be used as a reference for a research paper. So, when I highlighted the word ‘syllabi’, it came up with three options: Dictionary, Thesaurus, and Wikipedia. When I highlighted the word ‘syllabuses’, it came up with only two options: Dictionary and Thesaurus. I would trust using ‘syllabuses’ instead of ‘syllabi’ because the latter gave a Wikipedia option. Maybe this is a bad assumption, but from what Dr. Jerz said about octopuses vs. octopi, I would chose ‘syllabuses’ because we don’t follow the ‘i’ rule, we follow the ‘es’ rule.
Source: English: A Fluid Language