The state of being swollen, or the swelling itself — a part of the body filling up and getting bigger, usually because blood or fluid has gathered there. This is a formal, medical word; you will find it in medical writing and in careful literary prose, almost never in speech. Two things to know about how it is really used. First, in medicine it very often refers specifically to the swelling of sexual organs when a person is aroused; 'nocturnal penile tumescence' is a standard clinical term. Because of that, the word carries a strong sexual colour even when the writer did not intend one, so it is not a safe everyday substitute for 'swelling'. Second, writers sometimes use it about things that are not bodies at all — a swelling budget, a swelling ego — and there it usually sounds mocking, as if the thing has puffed itself up. The plain everyday words are 'swelling' and 'a lump'.

腫脹（正式、醫學用語；醫學上也常特指性器官充血勃起的狀態）