bad luck vs mishap

bad luck and mishap both are nouns.

Word	Noun	Adjective	Verb	Adverb
bad luck	Yes	No	No	No
mishap	Yes	No	No	No

As nouns, mishap is a hyponym of bad luck; that is, mishap is a word with a more specific, narrower meaning than bad luck:

bad luck: unnecessary and unforeseen trouble resulting from an unfortunate event
mishap: an instance of misfortune

As nouns, bad luck and mishap are synonyms defined as:

Other synonyms of bad luck include mischance.

bad luck (noun)	mishap (noun)
unnecessary and unforeseen trouble resulting from an unfortunate event	an instance of misfortune
an unpredictable outcome that is unfortunate	an unpredictable outcome that is unfortunate
an unfortunate state resulting from unfavorable outcomes