乎 is a modal particle (m.p.) from Classical Chinese, used at the end of a sentence to mark a question, exclamation, or rhetorical flourish — roughly equivalent to modern 吗 or 啊 in literary contexts. It is rarely used alone in everyday speech but appears in fixed idioms (不亦乐乎, 岂不悲乎) and in written or formal registers. The dictionary gloss 'to; at; with; than' actually reflects the Classical Chinese preposition 乎 (homograph of 于), which is a different sense. This row covers only the modal particle usage.