Definitions of unexpected:

• adjective:   not planned

  Example: "An unexpected pregnancy"

• adjective:   causing surprise or amazement by not being expected

  Example: "The curtains opened to reveal a completely unexpected scene"

• adjective:   not foreseen
• adjective:   not expected or anticipated

  Example: "Unexpected guests"

• adjective:   happening or coming quickly and without warning

  Example: "A sudden unexpected development"

• adjective:   made necessary by an unexpected situation or emergency