unforeseen

As an adjective unforeseen

is not foreseen.

As an initialism Swift is

society for worldwide interbank financial telecommunication.

As adjectives the difference between abrupt and unforeseen

is that abrupt is (obsolete|rare) broken away (from restraint) while unforeseen is not foreseen.

As a verb abrupt

is (archaic) to tear off or asunder .

As a noun abrupt

is (poetic) something which is ; an abyss .

As adjectives the difference between unforeseen and unannounced

is that unforeseen is not foreseen while unannounced is not announced.

As adjectives the difference between unforeseen and instantaneous

is that unforeseen is not foreseen while instantaneous is occurring]], [[arise|arising, or functioning without any delay; happening within an imperceptibly brief period of time.

As adjectives the difference between unforeseen and quick

is that unforeseen is not foreseen while quick is moving with speed, rapidity or swiftness, or capable of doing so; rapid; fast.

As an adverb quick is

(colloquial) with speed, quickly.

As a noun quick is

raw or sensitive flesh, especially that underneath finger and toe nails.

As a verb quick is

to amalgamate surfaces prior to gilding or silvering by dipping them into a solution of mercury in nitric acid.

As adjectives the difference between unexpected and unforeseen

is that unexpected is not expected, anticipated or foreseen while unforeseen is not foreseen.

As an adjective unforeseen

is not foreseen.

As a noun for is

oven.

As adjectives the difference between unforeseen and rapid

is that unforeseen is not foreseen while rapid is rapid; quick; fast; speedy.

As adjectives the difference between unforeseen and hasty

is that unforeseen is not foreseen while hasty is acting in haste; being too hurried or quick (eg without much thinking about it they made a hasty decision to buy it ).

As adjectives the difference between sudden and unforeseen

is that sudden is happening quickly and with little or no warning while unforeseen is not foreseen.

As an adverb sudden

is (poetic) suddenly.

As a noun sudden

is (obsolete) an unexpected occurrence; a surprise.