We don't have synonyms for iron ring yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are iron lung, ironing and ironizing.
(n) :
(Canada, engineering) The symbol of a Canadian engineer. A faceted stainless steel or iron ring worn on the little finger of the dominant hand, signifying a trained Canadian engineer, awarded in Canada after an accompanying oath of professional conduct, in a private ceremony with dramatic rites.
(n) :
Used other than figuratively or idiomatically: see iron, ring.
(n) :
(Canada, engineering) The symbol of a Canadian engineer. A faceted stainless steel or iron ring worn on the little finger of the dominant hand, signifying a trained Canadian engineer, awarded in Canada after an accompanying oath of professional conduct, in a private ceremony with dramatic rites.
(n) :
Used other than figuratively or idiomatically: see iron, ring.