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.
Learner's definition of HABIT. 1. : a usual way of behaving : something that a person does often in a regular and repeated way. [count] It was his habit to take a nap after dinner every evening. It's important that parents teach their children good study/eating habits.