sullen

Compared meaning: in a bad or unpleasant mood (adjective).

比较义项：情绪低落、脾气不好的（形容词）。

• moody

  Describes a person whose mood swings unpredictably between good and bad, not just anger; can be temporary or a lasting trait; doesn't imply silence or a specific trigger.

  形容一个人情绪变化无常，时好时坏，不仅限于生气；可以是暂时的状态，也可以是性格特点；不一定意味着沉默或有特定诱因。

  She's a moody artist, cheerful one minute and gloomy the next.

  她是个情绪多变的画家，前一分钟还兴高采烈，后一分钟就闷闷不乐。

• sullen 本词

  Describes someone who is silently resentful or sulky, often shown by a fixed, unsmiling expression and refusal to talk; a reaction to a specific slight or unhappiness.

  形容一个人因生气或不满而沉默、绷着脸生闷气，通常表现为面无表情、不愿说话；是对某件具体的不快或冒犯的反应。

  He sat in the corner with a sullen expression, refusing to speak to anyone.

  他坐在角落里，绷着一张愠怒的脸，谁都不理。

• irritable

  Describes someone with a low tolerance for annoyance, easily angered by small or trivial things, often due to tiredness, hunger, or illness; not about silence.

  形容一个人容忍度低，容易因小事而生气发怒，常常是因为疲惫、饥饿或生病；与沉默无关。

  The baby was irritable and kept crying over the smallest things.

  那个婴儿很烦躁易怒，一点小事就哭闹不停。

All three describe a bad mood, but differently. Moody means a mood that swings unpredictably, not always anger. Sullen means silently resentful, often shown by a fixed, unsmiling face and refusal to talk. Irritable means easily annoyed by small things, often from tiredness or hunger.

这三个词都可以形容人情绪不好、脾气差，但语气和适用场合不同：moody 强调情绪时好时坏、变化无常；sullen 强调因生气或不满而沉默、绷着脸不说话；irritable 强调容易被小事惹恼、缺乏耐心。