Quick is a related term of existent.
In archaic|lang=en terms the difference between quick and existent
is that
quick is (archaic) pregnant, especially at the stage where the foetus's movements can be felt; figuratively, alive with some emotion or feeling while
existent is (archaic) a being or entity that exists independently.
As adjectives the difference between quick and existent
is that
quick is moving with speed, rapidity or swiftness, or capable of doing so; rapid; fast while
existent is existing; having life or being, current; occurring now.
As nouns the difference between quick and existent
is that
quick is raw or sensitive flesh, especially that underneath finger and toe nails while
existent is (archaic) a being or entity that exists independently.
As an adverb quick
is (colloquial) with speed, quickly.
As a verb quick
is to amalgamate surfaces prior to gilding or silvering by dipping them into a solution of mercury in nitric acid.