gumshoe

the word 'gumshoe' is a compound formed from two english words. originally, 'gumshoe' literally referred to a shoe with a soft, rubbery sole, as 'gum' was a common term for rubber in the 19th century. this quiet, stealthy footwear became associated with detectives who needed to move silently while conducting surveillance. through this metonymic process, the term for the shoe was transferred to the person wearing it, solidifying its slang meaning for a detective by the early 20th century.

Structure: gum + shoe gum (english, from middle english 'gome', meaning 'man' or 'palate', later referring to a sticky substance); shoe (english, from old english 'scōh', meaning a protective covering for the foot)