かろう

かろう is an old-fashioned, literary conjectural auxiliary that means 'probably' or 'I suppose so,' similar in meaning to だろう but used in classical Japanese or in formal/literary contexts. It is not common in everyday modern speech. It attaches to the plain form of verbs and adjectives (and sometimes to na-adjectives in the sense of the predicative form). The nuance is more tentative, contemplative, or like a guess in narration rather than a firm assertion. Typical contexts include historical writing, fiction set in classical periods, or stylistic usage to evoke antiquity.