This is for Christi
Here is a fairly easy word to trace, but that does not make it any the less interesting. It came into English fairly late, only arriving in the late 14th century. At that time it was used in the singular – mathematic. It wasn’t until around two centuries later that the plural form mathematics came to be preferred.
English took it from Latin mathematica, which is a plural form in Latin, and this fact does explain the shift towards the plural in English, but not why the singular form was initially used. The word did not start off in Latin, it came from Greek μαθηματική τέχνη (mathematiki techni), which means “mathematical art”, or “science”, if you prefer.
The term μαθηματικά (mathematika) was already in use in Greek in around 450 BC. We know this from references found in Aristotle to (now lost) work by Democritus, cited as μαθηματικά (mathematika).
It comes from μάθημα (mathima), a noun meaning “lesson, science”, or even more literally “what is learnt”, as it derives from the verb μανθάνω (manthano), meaning “to learn”. This has stayed very close in modern Greek, where it is now μαθαίνω (mathaino).
The story does not end here. We can further trace the root to Proto-Indo-European *men- or *mendh, probably meaning “think”, a stem that has given rise to a whole host of vocabulary, in a number of languages, generally related to the mind. From here comes Latin mens, meaning “mind”, which is where English word mental derives from, as well as Spanish and Italian mente. Not only that, but it has even left its traces in Welsh, where we find mynnu; “insist” or “persist” – just the attitude you need when tackling a difficult task from its distant cousin mathematics!