suffix, na-adjective
Suffix that attaches to adjective stems, mimetic words, or certain nouns to form a na-adjective expressing a state or quality. Common in words like 高らか (tall/loud), 清らか (pure/clean), 朗らか (cheerful). Not freely productive; limited to specific lexicalized combinations.
「高らか」の「らか」は、状態を表す接尾辞です。
The らか in 高らか is a suffix that expresses a state.
「清らか」や「朗らか」のように、限られた語に付きます。
It attaches to a limited set of words, as in 清らか and 朗らか.