caffeine
UK[ˈkæfiːn]US[kæˈfiːn]
n
a chemical substance found in coffee and tea that makes you feel more awake
Etymology
The word 'caffeine' is a modern scientific coinage from the early 19th century. It was formed in German as 'Kaffein' from 'Kaffee', the German word for coffee, which itself originates from the Ottoman Turkish 'kahve', borrowed from Arabic 'qahwa'. The suffix '-in' is a standard German (and international scientific) suffix used to name chemical substances, such as protein or insulin. Thus, the term's literal logic is transparent: "the chemical substance found in coffee."
Analysis
The word is a simplex loanword. It is derived from the German 'Kaffein', itself formed from 'Kaffee' (coffee) + the chemical suffix '-in' (denoting a neutral chemical compound).
Examples
Coffee and tea are common sources of caffeine.
She avoided caffeine in the evening to help her sleep.
The doctor recommended reducing his caffeine intake.