Vigour is strong, healthy energy — the kind that shows. It covers the body (an old woman who still walks up the mountain has vigour), the mind (a writer whose thinking is still sharp at eighty), and the force someone puts into an activity ('he defended his idea with great vigour'). It is an uncountable noun: some vigour, a lot of vigour, never *a vigour* and never *vigours*. The word carries a warm, admiring feeling; it is usually said about someone we respect. It is also a bit formal and literary — in conversation a Taiwanese student would more often say energy, or 'she's still really active'. Two very common patterns are worth memorising: 'with vigour' (doing something forcefully) and 'full of vigour' (describing a person). Americans spell it vigor.