spiegeleisen vs spiegel iron

spiegeleisen and spiegel iron both are nouns.

Word	Noun	Adjective	Verb	Adverb
spiegeleisen	Yes	No	No	No
spiegel iron	Yes	No	No	No

As nouns, spiegeleisen and spiegel iron are synonyms defined as:

spiegeleisen and spiegel iron: pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel

Other synonyms of spiegeleisen include spiegel.

spiegeleisen (noun)	spiegel iron (noun)
pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel	pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel