Impossible to detect by olfaction (9)
I believe the answer is:
odourless
(Other definitions for odourless that I've seen before include "Without smell" , "Without so much as a whiff" , "Lacking smell" , "devoid of smell" , "free from smell" .)
I believe the answer is:
odourless
(Other definitions for odourless that I've seen before include "Without smell" , "Without so much as a whiff" , "Lacking smell" , "devoid of smell" , "free from smell" .)