lash-up vs contrivance

lash-up and contrivance both are nouns.

Word	Noun	Adjective	Verb	Adverb
lash-up	Yes	No	No	No
contrivance	Yes	No	No	No

As nouns, lash-up and contrivance are synonyms defined as:

lash-up (noun)	contrivance (noun)
any improvised arrangement for temporary use	the act of devising something
	a device or control that is very useful for a particular job
	any improvised arrangement for temporary use
	an elaborate or deceitful scheme contrived to deceive or evade
	the faculty of contriving; inventive skill
	an artificial or unnatural or obviously contrived arrangement of details or parts etc.