Connotation
the emotional or cultural associations a word carries beyond its literal meaning
Denotation
the literal, dictionary meaning of a word, without emotional associations
Amelioration
a process by which a word gains a more positive meaning over time
Pejoration
a process by which a word gains a more negative meaning over time
Examples
Connotation: "house" is neutral; "home" has warm connotations.
The denotation of "snake" is a reptile; its connotation may be treachery.