stainless (adj.)youdaoicibaDictYouDict[stainless 词源字典]
1580s, from stain (n.) + -less. Related: Stainlessly. Stainless steel is from 1917, a chromium-steel alloy (usually 14% chromium) used for cutlery, etc., so called because it is highly resistant to rust or tarnish.[stainless etymology, stainless origin, 英语词源]