shackle vs irons

shackle and irons both are nouns.

Word	Noun	Adjective	Verb	Adverb
shackle	Yes	No	Yes	No
irons	Yes	No	No	No

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

shackle: a restraint that confines or restricts freedom (especially something used to tie down or restrain a prisoner)
irons: metal shackles; for hands or legs

Other hyponyms of shackle include ball and chain, fetter, hobble, cuff, handcuff, handlock, manacle, chains.

shackle (noun)	irons (noun)
a restraint that confines or restricts freedom (especially something used to tie down or restrain a prisoner)	metal shackles; for hands or legs
a U-shaped bar; the open end can be passed through chain links and closed with a bar

shackle (verb)	irons (verb)
restrain with fetters
bind the arms of