'stainless steel' is a compound of 'stainless' and 'steel'. 'stainless' originates from English 'stain' + suffix '-less', where 'stain' meant 'to blemish or discolor' and '-less' means 'without'. 'steel' originates from Old English 'stēle' (also spelled 'stæle'), from Proto-Germanic '*stahliją' meaning 'hard metal'.

'stainless' developed in Middle English as a negative adjective meaning 'without stain'; 'steel' comes from Old English 'stēle' and cognates in other Germanic languages. The specific compound 'stainless steel' arose in the early 20th century to name newly developed corrosion-resistant alloys (notably after Harry Brearley's work in 1913 in Sheffield).

Initially, 'stainless' simply meant 'without stain or blemish'; when combined with 'steel' in the 20th century, it took on the specific technical meaning of a steel alloy that resists staining and rusting, now the common modern sense.