Blog. A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today. Definition and synonyms of all-American from the online English dictionary from Macmillan Publishers Limited.0% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class of psychoactive drugs. It is the world's most widely consumed psychoactive drug, but unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world.affeine's biological half-life â the time required for the body to eliminate one-half of a dose â varies widely among individuals according to factors such as pregnancy, other drugs, liver enzyme function level (needed for caffeine metabolism) and age. In healthy adults, caffeine's half-life is between 3â7 hours.
Caffeine is the most widely consumed stimulating substance in the world. It is found in coffee, tea, soft drinks, chocolate, and many medications. Caffeine is a xanthine with various effects and mechanisms of action in vascular tissue.