sieve vs riddle

sieve and riddle both are nouns.

Word	Noun	Adjective	Verb	Adverb
sieve	Yes	No	Yes	No
riddle	Yes	No	Yes	No

As nouns, riddle is a hyponym of sieve; that is, riddle is a word with a more specific, narrower meaning than sieve:

sieve: a strainer for separating lumps from powdered material or grading particles
riddle: a coarse sieve (as for gravel)

Other hyponyms of sieve include sifter, dirt sifter, soil sifter.

As verbs, riddle is a hyponym of sieve; that is, riddle is a word with a more specific, narrower meaning than sieve:

sieve: separate by passing through a sieve or other straining device to separate out coarser elements
riddle: separate with a riddle, as grain from chaff

Other hyponyms of sieve include rice, resift, screen, winnow.

sieve (noun)	riddle (noun)
a strainer for separating lumps from powdered material or grading particles	a coarse sieve (as for gravel)
	a difficult problem

sieve (verb)	riddle (verb)
distinguish and separate out	explain a riddle
separate by passing through a sieve or other straining device to separate out coarser elements	set a difficult problem or riddle
check and sort carefully	speak in riddles
examine in order to test suitability	pierce with many holes
	separate with a riddle, as grain from chaff
	spread or diffuse through