Dictionary definitions of Stainless Steel – What is it really?

Stainless steel – Function: noun Date: 1920
an alloy of steel with chromium and sometimes another element (as nickel or molybdenum) that is practically immune to rusting and ordinary corrosion
Merriam-Webster’s WWWebster Dictionary

Stainless steel – any one of three types of steel that contain a high percentage of chromium (up to about 25%), making them resistant to rusting and abrasion and possessing a high tensile strength.
AND Concise Dictionary

Stainless steel – Any of various steels alloyed with at least 10 percent chromium and sometimes containing other elements and that are resistant to corrosion or rusting associated with exposure to water and moist air.
The American Heritage® Dictionary of the English Language: Fourth Edition. 2000

Stainless steel – Pronunciation: sten lihs stil
Noun: an alloy of steel and chromium, which is resistant to rust and corrosion
Wordsmyth English Dictionary

Stainless steel – Corrosion resistant steel of a wide variety, but always containing a high percentage of chromium. These are highly resistant to corrosion attack by organic acids, weak mineral acids, atmospheric oxidation, etc.
Metalmart

Stainless steel Metallurgy – any of a group of ferrous alloys that contain at least 12% chromium, providing good corrosion resistance in the presence of oxygen and absence of chloride ions.
Academic Press Dictionary of Science and Technology