What does 我慢 Gaman mean?

Gaman means enduring something difficult without complaining about it. The characters say something else entirely, and the gap between them is the most interesting fact about the word.

The characters, and the original sense

我 (ga) is self, or ego. 慢 (man) is pride or arrogance. Together, in the Buddhist vocabulary the compound came from, they named self-conceit: the stubborn attachment to one's own importance, listed among the mental afflictions a practitioner works to subdue.

So the word began as the name of a fault. Specifically the fault of an ego that will not yield.

How a fault became a virtue

The route is not mysterious once stated. An ego that will not yield is also an ego that will not break, and the same stubbornness that looks like arrogance from one angle looks like fortitude from another. Japanese usage kept the immovability and shed the disapproval.

What survives in modern use is a compliment: the person who bears the illness, the winter, the long shift or the grief without making it everyone's problem. The pride is still in there, quietly, since a large part of what is being endured is the wish to complain.

The romanticised version, and its cost

English writing about Japan reaches for this word often, usually to admire it, and often in contexts where admiration is the wrong response. Endurance is a virtue when the thing endured is unavoidable. It is something else when the thing endured is a workload, an abusive supervisor or a system that depends on people not complaining.

Japanese discourse is perfectly capable of making that criticism and does. Writing that treats the word as a pure national virtue tends to import the approval without the argument, which flattens a live domestic debate into a decorative trait.

What English has instead

Several partial matches and no whole one. Stoicism carries the philosophy and not the everyday register. Grin and bear it is the right level and too light. Toughing it out is close and sounds like a choice, where this often describes a duty.

The missing element in all of them is the audience. This word implies other people who are being spared, which is why it functions socially rather than personally, and why it can be demanded of someone as well as praised in them.