Semantic Change
BROADENING/GENERALISATION:
A word keeps its original meaning but also takes on additional meanings.
NARROWING/SPECIALISATION:
The opposite of broadening: a word becomes more specific in its meaning.
AMELIORATION:
The meaning of a word becomes more positive or pleasant.
PEJORATION:
The meaning of a word becomes more negative or unpleasant.
WEAKENING:
Words lose some of their force or strength.
METAPHOR:
Words acquiring new meanings because they are frequently used in a metaphoric way.
IDIOMS:
Phrases formed from pre-existing words, which usually have an everyday use or meaning and often have interesting origins.
EUPHEMISMS:
A valid, inoffensive or more pleasant way of describing something distasteful or unpleasant. (Opposite = dysphemism)