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.
Q: I saw an article today that prompted a thought. I only took a year of Latin in high school, so I want to run this by some other people. The article referenced a female senator so-and-so. However, I think that senator, with the -or ending is in the nominative, third declension, which is not gender neutral. So, when referring to a female subject, should senatrix be used instead? Also, does anyone know if there is a reason why the male form is used exclusively? I think females were restricted from the Roman senate perhaps the term just never made sense etymologically because of this?.
A: 
A number of answers have addressed the fact that in the United States, the use of gender-specific nouns is becoming less fashionable. However, that does not explain why a female equivalent of senator has never existed, only why if it did exist once, it might be less favoured now. I try to answer the etymological question here in relation to senatrix. There is no classical support for senatrix. The word senator was, both originally in English and in Latin, an expression referring exclusively to males, simply for the unfortunate dearth of female senators. In classical Rome, a senator (Latin senator) was always a man, and when the word later came to be used to refer to members of foreign legislatures, to my knowledge all such references were to men. Indeed senator itself essentially meant 'elderly man', from senex, 'old, elderly'. The obvious female equivalent, senatrix, does appear in Lewis & Short, but a brief search on Perseus suggests it is not attested in any major classical source. Of course, Rome had two famous female senators in the tenth century mediaeval senate (or what was left of it), and indeed senatrix was the formal title used by Theorda and Marozia, her daughter*. But they are an anomaly, and were I think of little interest when the word senator was imported into English and first popularized. Therefore we begin with a situation in which anyone who read Latin would know that senatrix was not a classical word, and those of us who delight in imposing arcane Latin grammar rules on unsuspecting English speakers are equally reluctant to pollute the lexicon with artificial Latin words [and anything after August 476 AD doesn't count]. On the use of senatrice in French. The French word sometimes used for a female senator (senatrice) appears to be a backformation from senateur + -trice rather than derived directly from *senatrix. That said, senatrice is long established in the French language, appearing in the 1762 edition of the dictionnaire de L'Academie francaise. This is curious, as in 1762 the ancien regime remained strong and the date long precedes the the establishment of the French Senat in 1799. However my knowledge of French and France is embarrassingly poor, so all I shall say is that 1762 is long after the word senator appeared in English. Therefore senator had become an English word by this time, and I suggest that the continuing evolution of its cognate in French would have had limited effect on the use of senator in English. The Academie francaise now discourages the use of senatrice. There is little use of senatrix at any time in English. A Google Ngram search reveals that senatrix did have a brief period of use in the early twentieth century, around the time that the notion of female senators entered the public discourse. However, a more detailed inspection reveals that this seems to be an upswing in interest about Theodora and Marozia, rather than in the composition of the modern legislature. In that search I did find one tantalizing reference to the 'senatrix from Kansas', but as the reference dates from 1898, eighty years before the first female senator from Kansas, and is entitled 'Judge's Library: A Monthly Magazine of Fun', it cannot be taken at face value. senatrix has little in the way of a history and less in the way of a future. Lacking a sound etymological past, senatrix was not popular among those most likely to have adopted it; and until 1932 there was regrettably very little need for the word to be used at all in popular discourse. As the other answers carefully elucidate, in English, particularly American English, there is a trend away from long-established gender-specific words, so it seems quite unlikely we will see the adoption of any artificial ones any time soon. *You may recall that Gibbon famously describes them in Decline and Fall as 'sister prostitutes', but later sources are quite clear that they were mother and daughter. Gibbon does not use the word senatrix as far as I can see.