Yamato kotoba
Since on'yomi came from Chinese monosyllables (words with only one syllable), they themselves are also only one syllable, and like Chinese, they can have a CV or CVC structure. For example, the on'yomi for the following kanji 刀, 魚, 紙, 山, 手, and 泳 are tō, shi, san, shu, and ei. However, kun'yomi can have one or multiple syllables, and those syllables are usually a CV structure, like the examples given above.