What is the meaning of Iron_group?

Any of several groupings of elements that share traits with iron in one way or another.

1. Row 4 (period 4) of the periodic table, or a large subset thereof.
   1. A smaller subset thereof comprising iron, cobalt, and nickel.

      Row 4 (period 4) of the periodic table, or a large subset thereof.

      1. A smaller subset thereof comprising iron, cobalt, and nickel.

         A smaller subset thereof comprising iron, cobalt, and nickel.

         Group 8 of the periodic table, comprising iron, ruthenium, osmium, and hassium.

         Source: wiktionary.org