奇怪

奇怪 (qíguài) is the adjective for 'strange,' 'odd,' or 'weird' — describing something that surprises you because it doesn't fit expectations. It applies broadly: a strange smell (奇怪的味道), strange behavior (奇怪的行为), a strange feeling (奇怪的感觉). It can also function as a verb of inner experience: 我很奇怪他为什么不来 ('I find it strange why he didn't come'). Two distinctions for English speakers: first, 奇怪 carries puzzlement more than judgment — it means 'this is unexpected,' not necessarily 'this is bad' (compare 'weird' in English, which can sound dismissive).

Second, the exclamatory 奇怪！on its own is extremely common — like English 'That's weird!' when something goes wrong (a missing key, a closed shop). Both characters mean 'strange,' so the compound is doubled for emphasis.