A spender is someone thought of in terms of how they use their money. Like 'speller', it hardly ever stands alone — it comes with a describing word: 'a big spender', 'a careful spender', 'a reckless spender'. 'A big spender' is by far the most common, and it carries a warm, slightly teasing tone: someone who pays for everyone's dinner, who buys the expensive one without looking at the price. It can be a compliment ('he's a big spender, very generous') or gentle mockery — if a friend buys you a cheap drink, you might say 'Oh, big spender!' with a smile, meaning the opposite. In business and news writing, 'spender' turns cold and factual: shops talk about 'high spenders' or 'top spenders', meaning the customers who bring in the most money, and news reports call a country 'the biggest defence spender in the region'. So the same word is friendly at a dinner table and purely numerical in a report.