Vocabulary What does 酵母 (こうぼ, koubo) mean? 酵母 (こうぼ, koubo) means yeast; leaven. Quick factsReadingこうぼRomajikouboPart of speechnoun 酵母こうぼkouboyeast; leaven1noun yeast; leavenKanji in this word酵fermentation, yeast母mother