stainless
Word family
Synonym discussion
Sense: adjective/1
All four words describe freedom from marks or damage, but they differ in scope. 'Rustproof' is the narrowest term, referring only to a material's ability to resist corrosion — you can call a chain 'rustproof' but not a countertop that merely looks clean. 'Spotless' emphasises the visual result: a surface with no spots or stains at all, whether or not it is resistant to future damage. 'Untarnished' historically applied to metals whose shine had not dulled, but it is now also used figuratively (e.g. 'an untarnished reputation'). 'Immaculate' suggests a higher degree of perfection, often implying that something has been carefully cleaned or is completely without flaw. For example, a chef's 'immaculate apron' looks freshly pressed and stain-free, while a 'stainless steel pan' might be 'stainless' by material but not necessarily 'immaculate' at the moment.
Etymology
Formed in English from the noun 'stain' (meaning a mark or discolouration) plus the suffix '-less' (meaning 'without'). 'Stain' came into English from Old French 'deinteindre' (to discolour or dye), which itself traces back to Latin 'dis-' (apart) + 'tingere' (to dye or colour). The word originally described physical marks, and the figurative moral sense developed later in English.