A taskmaster is a person who gives other people work and makes sure they do it — and the word almost always says something about how hard they push. Nine times out of ten you will meet it in the phrase 'a hard taskmaster' or 'a tough taskmaster': someone who demands a great deal, sets a high standard, and does not let you slack off. The tone is interesting, because it is not simply an insult. Calling your old teacher a hard taskmaster can be a kind of respect — she worked us to the bone, and look what we learned. Calling your boss one is usually a complaint. The word is slightly old-fashioned and formal-sounding, which is part of why it survives in that fixed phrase rather than as an everyday job title; nobody's business card says 'taskmaster'. It stretches nicely, too: English speakers use it for things that are not people at all. 'The sea is a hard taskmaster.' 'Time is a cruel taskmaster.' The idea is that the thing sets demands you cannot argue with. Note the definition given here is written as a verb — 'to force people to work very hard' — but the word itself is a noun. It names the person who does that forcing. Behind it sits a much older and darker use, for the overseer who drove slaves at their work, which is why the word still carries a faint sense of no choice in the matter.