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.
When you do something strenuously, you work really hard at it. After working strenuously on your neighbor's farm all day, you'll be exhausted and ready for a break. The adverb strenuously is good for describing activities or actions that require hard work. You can play strenuously during your high school football team's final game, working up a sweat, or you can argue strenuously during a debate. In either case, what you're doing is seriously demanding.