jiffy vs mo

jiffy and mo both are nouns.

Word	Noun	Adjective	Verb	Adverb
jiffy	Yes	No	No	No
mo	Yes	No	No	No

As nouns, mo is a hypernym of jiffy; that is, mo is a word with a broader meaning than jiffy:

jiffy: a very short time (as the time it takes the eye to blink or the heart to beat)
mo: an indefinitely short time

Other hypernyms of jiffy include bit, minute, moment, second.

jiffy (noun)	mo (noun)
a very short time (as the time it takes the eye to blink or the heart to beat)	an indefinitely short time