The attendant rules for the words may, or may not be carried to the new language. For example, many French words carry their plurals into English, while some more recent additions adopt English rules for pluralization
So we create new words or meanings as needed, and we drop old ones as they become obsolete or lose their usefulness. Another way language changes is by attitude. Cultural influences make certain words taboo, so we develop euphemisms to replace the taboo word. When the euphemism becomes widely known, we change it. One example in English is the word for toilet: water closet->loo->lavatory->ladies' room-> rest room ad infinitum until finally, we stopped thinking of this particular place as taboo in western society, so now we use many of the previous euphemisms as our personal taste dictates, and most people understand us.
Language is so basically part of our culture that culture is probably the strongest factor in its change. One of the early philosophers named language as a factor which, if destroyed by a conqueror, would help to absorb the target population. This is a strong factor in the linguistic battles still being fought in Canada between French and English, and a reason why people from countries previously occupied by the Soviet Union hate the Russian Language. Both dominant populations made historical attempts to destroy the language of the less dominant population. However, even today, as populations dominate in local areas, their particular linguistic lexicon, syntax and vernacular are adopted by border populations and those who stay a while and then migrate elsewhere. Words and linguistic rhythms entered English through use in inner city areas, and have been spread my M.T.V. And other mass media.
Languages are always changing. Twenty generations separate us from Chaucer. If we could board a time machine and visit him in the year 1390, we would have great difficulties in making ourselves understood-even roughly."(Keller, 1994, p. 3)
It is the arbitrariness factor of language that makes it change so fast, and, in fact, makes change necessary. We convey meaning in many ways incidental to language: body language, tone of voice, accidental or intentional mispronunciation (e.g. negra vs. negro as a derogatory label) and even simple word association. Meanings may become popular, then become derogatory and then popular again as the culture changes. The word "wench," of British origin, is a case in point. It originally referred to a girl who worked, particularly at manual or farm labor. Then it became popular as a label for all young women. Women became aware of it and did not like being called wenches, so it became derogatory and unpopular. Then, in the 19602, it became complementary and popular again, by virtue of its use in popular song and poetry. Now it is again out of use, because tastes changed.
Keeping up with the changes in even one language is a daunting task, because the very technology which helps us keep up has accelerated that change process. New words are invented daily and spread via mass media. Writers coin new words or meanings and these are also popularized by the media. Population move around the globe, creating megalopolises of many different cultures mixed all together. Music and literature are translated and shared, adding new words to the target languages. Technology requires the creation of new words to identify new objects, action or attributes. Cultural changes make some words taboo and some popular. Global travel and business changes the language of both populations. Political and cultural forces change the lexicon and the accents of our language. Words are added from acronyms and other languages and their origins are forgotten, but the words stay in use until something else takes their place. It is said that only dead languages, like Latin, do not change, so we have learned to adapt to constant change in our language and even to cause it.