yó
yí is a Mandarin syllable in the second tone, written in pinyin as yí. It represents many different Chinese characters, so it is not a single word but a pronunciation shared by several morphemes. In modern Mandarin, words containing this reading gain meaning from the specific character that carries the yí sound.
Common characters with the pronunciation yí include: 疑, meaning doubt; in words such as 疑问 (yíwèn) and 疑似 (yísì).
Because yí covers many characters with distinct meanings, context and characters determine the meaning in any