Definitions of really:

• adverb:   used as intensifiers; `real' is sometimes used informally for `really'; `rattling' is informal

  Example: "A really enjoyable evening"

• adverb:   in fact (used as intensifiers or sentence modifiers)

  Example: "Really, you shouldn't have done it"

• adverb:   in actual fact
• adverb:   in accordance with truth or fact or reality

  Example: "They don't really listen to us"