TASK DEFINITION: Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
PROBLEM: What is the antonym of the word destination. Here is some context: Every train has a destination and a ____? I was thinking it might be origin but I've never encountered that word used in this context so I'm not sure - there might be a better word.

SOLUTION: According to a Google search, the word origin is used as the opposite of destination on several pages on the Amtrak web site. Amtrak is the largest train operator in the United States. Here are a few examples: This schedule lists the Origin and 'Destination' of various routes. The Interactive Route Atlas page says the following: Once you have selected origin and destination stations by one of the methods above, click on the 'Go' button to send your custom route request. The Multi-Ride Ten-Ride Ticket page says the following: Ten-ride tickets are valid for ten rides within a 45-day, 60-day or 180-day period depending on your origin and destination cities.

PROBLEM: In math, we use the term series a lot, and there are many types of series. How should I craft my sentence when I have three different ones in mind to talk about? Should I settle down for a less mortal alternative of 'list of series' or something like that? The existing question on The possessive and plural forms of 'series' suggests the usage of series'. But is that all? If that's the only solution, then could you please explain the usage of apostrophe symbol at the end? Is that a plural marker or a possessive marker, or both?.

SOLUTION: Series (like deer, salmon, and sheep) is pronounced and spelled the same in the plural as in the singular. If either the singular or the plural is used as a possessive, an apostrophe is added to show that in print, though there is no pronunciation difference in speech. Thus, The series doesn't converge. (singular) The series don't converge. (plural) This series' limit is unknown. (singular possessive) These series' limits are unknown. (plural possessive) More examples can be seen here.

PROBLEM: I know that Sussex and Middlesex are in England. It looks to me as if there is a pattern in names. What does the suffix -sex mean? Where does it come from?.

SOLUTION:
The -sex suffix is from Anglo-Saxon / Old English, with the actual meaning being 'Saxon'. Sussex is essentially 'South Saxon'. Middlesex is 'Middle Saxon'. Essex is 'East Saxon'. Wessex is 'West Saxon'. Most of the wiki pages for these places will have the toponymy definition.