Being as nerdy about words as I am, I find it interesting to get into details like why the parts of speech are called what they are. Hence this post, which will be in two parts because there are a lot of details to get into.
Verb first showed up in English in the late fourteenth century. It came from the Old French verbe, which had the same meaning (not a big jump there). Verbe came from the classical Latin verbum—a word and can be traced even further back to the Proto Indo European were(side note: verbum is also the origin word for verbatim; both literally mean “word for word”). Adverb showed up a little later, in the early fifteenth century. It came from the Late Latin adverbium, a translation of a Greek word. It’s combination of verbum and the prefix ad- (to, at), which can be thought to mean to a verb or “that which is added to a verb.”
Noun also showed up in the late fourteenth century, from the Old French nom and the classical Latin nomen. Appropriately enough, both of those mean “name.” Pronoun, of course, is the same word with a shiny new prefix. It showed up a little later, in the early fifteenth century. Pro- has several meanings, including “in place of,” making the word “in place of a noun.”
The final word we’ll be looking at today is adjective. The word itself showed up in the late fourteenth century from the Old French adjectif and the classical Latin adjectivum. Adjectivum comes from another Latin word, adicere, which means “to throw or place near.” It’s a combination of icere “to throw” and the prefix ad-. It has a slightly different meaning than in adverb. Here it means to, as in “to throw to.”
Have you noticed they all showed up around the same time? It’s worth noting that the time period is just after the invention of the printing press in 1440. Before books were mass produced, very few people had the need to read and write (oh, how mind-numbing it must have been). And so, very few people had the need to qualify language. Then grammar came along and the rest is history.