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.
Active, energetic, strenuous, vigorous imply a liveliness and briskness in accomplishing something. Active suggests quickness and diligence as opposed to laziness or dilatory methods: an active and useful person. Energetic suggests forceful and intense, sometimes nervous, activity: conducting an energetic campaign. Strenuous implies arduous and zealous activity with a sense of urgency: a strenuous effort. Vigorous suggests strong, effective activity: using vigorous measures to accomplish an end. 4. agile, sprightly.