Applied to words — a report, a letter, a reply, a defeat — stinging means very harsh, sharply critical, and painful to be on the receiving end of. A stinging report on a hospital does not politely suggest improvements; it names failures. A stinging rebuke is a telling-off that leaves a mark. A stinging defeat is a loss that humiliates.

The picture behind it is straightforward and worth holding on to. A bee sting is small — it does not break your bones — but it is sudden, sharp, and it goes on hurting afterwards. Stinging criticism is the same shape: it is not long or violent, it is precise, and it lands. That is why stinging goes so naturally with attack, criticism, rebuke, and defeat, and awkwardly with things that are merely long or unkind.

This is newspaper and formal-writing language above all. "In a stinging attack on the government…" is close to a fixed opening in British journalism. In everyday speech people would say harsh or brutal instead.

The literal senses live alongside it and are more common in daily life: a stinging pain (sharp and burning — antiseptic on a cut, cold wind on your face), and stinging as the ordinary -ing form of the verb ("the smoke was stinging my eyes"). British English also has the stinging nettle, a plant that burns your skin if you touch it, which every British child learns about the hard way.