Semantic change is the evolution of word usage. Semantic change is change in one of the meanings of a word. When features are dropped, this is called widening. Widening may result in either more homonymy or in more polysemy. Semantic widening broadens the meaning of a word. This process is called "generalization."  Some factors that affect semantic widening are linguistic factors, psychological factors, sociocultural factors, and cultural/encyclopedic factors.
Most personal names undergo widening. Most companies are named after the principle people who first created the company. Over time, as the company becomes more and more famous, the name is known all over the world. Eventually, this company's name becomes an example of semantic change.
A lexeme widens its meaning. A lexeme is a unit of lexical meaning. The headwords in a dictionary are all lexemes.
- Kleenex - The name of the soft facial tissue of the Kimerly-Clark Corporation
- Guy - Guido (Guy) Fawkes was the leader of the plot to blow up the English Houses of Parliament. The word "guy," eventually came to mean "a person of grotesque appearance." Over time, the word came to mean "a man or a boy."
- Demagogue - Originally meant "a popular leader". It is from the Greek demagogos (leader of the people), from demos (people) + agogos (leader). Now the word has a strong meaning of a politician who panders to emotions and prejudice.
- Gay - Originally meant feelings of being "carefree", "happy", or "bright and showy." The term later began to be used in reference to homosexuality, in particular, from the early 20th century.
- Democrat - At the time of the American Revolution, the term "democrat" had all the negative connotations of the modern usage of the word "demagogue". A century later, the term had shifted in meaning enough that it was viewed favorably as the name of an American National Political Party.
- Egregious - Originally described something that was very good. The word is from the Latin egregius (outstanding) which is from e-, ex- (out of) + greg- or grex (flock). Now it means something that is very bad.
- Business - A word that meant "busy, careworn, or anxious," and now means "a corporation or occupation."
- Cool - The slang word that meant "a jargon of jazz musicians." Over time, and then over time it began to mean a general word to describe something preferable.
- Expedite - (ex-, "from" + ped-, "foot") as we have seen, originally meant "to free one caught by the foot," but now refers to the removal of any sort of difficulty
- Assassin - a word which entered the languages of Europe during the Crusades, when members of a certain Mohammedan sect, having vowed the killing of Christian leaders, made use of the narcotic hashish to work themselves into a state of frenzy sufficient for the dangerous task. Assassin consequently first meant "eater of hasish," then a special fgroup of "hasish-eating terrorists" and finally any "treacherous murdererr" whether under the influence of drugs or not. ()
- English Words from Latin and Greek Elements by Donald M. Ayers 1986
Morphological: Folk etymology