AM and PM are associated with 12-hour timekeeping, as opposed to the international 24-hour clock. The 12-hour system grew up mainly in Northern Europe, and spread globally from there via the British Empire.
The adjective STRENUOUS has 2 senses: 1. characterized by or performed with much energy or force. 2. taxing to the utmost; testing powers of endurance. Familiarity information: STRENUOUS used as an adjective is rare.
Stimulants are a class of psychoactive drug that increase activity in the brain. These drugs can temporarily elevate alertness, mood and awareness. Some stimulant drugs are legal and widely used. Many stimulants can also be addicting.