Yes, iron is playable
...and is worth 5 points.
Found in the following dictionaries
Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Iron" Definition
noun
A metal appliance with a handle and a weighted flat bottom, used when heated to press wrinkles from fabric.
A silvery-white, lustrous, malleable, ductile, magnetic or magnetizable, metallic element occurring abundantly in combined forms, notably in hematite, limonite, magnetite, and taconite, and used alloyed in a wide range of important structural materials. Atomic number 26; atomic weight 55.845; melting point 1,535°C; boiling point 2,750°C; specific gravity 7.874 (at 20°C); valence 2, 3, 4, 6. See Table at element.
A tonic, pill, or other medication containing iron and taken as a dietary supplement.
An implement made of iron alloy or similar metal, especially a bar heated for use in branding, curling hair, or cauterizing.
adjective
Holding tightly; very firm: has an iron grip.
Inflexible; unyielding: iron resolve.
Made of or containing iron: iron bars; an iron alloy.
Strong, healthy, and capable of great endurance: an iron constitution.
Of, relating to, or made of iron.
idiom
In irons Nautical Lying head to the wind and unable to turn either way.
Iron in the fire An undertaking or project in progress: has many irons in the fire this year.
phrasal-verb
Iron out To settle through discussion or compromise; work out.
verb-transitive
To fit or clad with iron.
To press and smooth with a heated iron: iron clothes.
To put into irons; fetter.
To remove (creases) by pressing.