unexpected

not expected or anticipated

• “unexpected guests”
• “unexpected news”

not foreseen

• “unsuspected difficulties arose”
• “unsuspected turnings in the road”

made necessary by an unexpected situation or emergency

• “a forced landing”

causing surprise or amazement by not being expected

• “the curtains opened to reveal a completely unexpected scene”

not planned

• “an unexpected pregnancy”

happening or coming quickly and without warning

• “a sudden unexpected development”