のみならず

1. 1The statement applies not only to X but also to Y.Ex. 1
2. 2At the start of a sentence, it adds a further point to the preceding statement.

A formal, chiefly written expression used in contexts such as reports and speeches. Compared with だけでなく or ばかりでなく, it sounds more literary; the added item is often marked with も.

• のみかN2「のみか」is also literary and interchangeable with 「のみならず」when attaching to words to add information, but it cannot be used alone at the start of a sentence to mean 'not only that,' and it can also express escalation in degree, i.e., reaching an even worse state.
• ばかりでなくN3「ばかりでなく」has the same meaning and is interchangeable when attaching to words. Its register is neutral, working in both speech and writing without sounding stiff; na-adjectives can take 「な」directly (「静かなばかりでなく」) without adding 「である」.
• ばかりかN3「ばかりか」also means 'not only... but also...' and is interchangeable in most cases. It carries a sense of surprise—'even this...'—and the second item is often something further or unexpected. Its register is more colloquial than 「のみならず」, and na-adjectives can take 「な」directly, as in 「親切なばかりか」.
• だけでなくN3「だけでなく」is synonymous and interchangeable when attaching to words, works in both speech and writing, and is more natural in conversation; na-adjectives attach as in 「便利なだけでなく」. However, sentence-initial 「のみならず」meaning 'not only that' cannot be directly replaced with it.
• はもちろんN3「はもちろん」is common in both speech and writing and emphasizes that the first item is a matter of course; it mainly attaches to nouns (possibly with case particles). 「のみならず」is more formal and can also attach to verbs and adjectives and appear at the start of a sentence. When attaching to nouns, the two are mostly interchangeable.
• はおろかN1「はおろか」presents a difficult X first, then a more basic Y, emphasizing that even Y is impossible, usually with a negative nuance; 「のみならず」is a neutral addition of scope that works with both positive and negative content. Verbs take 「の」before 「はおろか」.

のみか is similarly formal; だけでなく and ばかりでなく are more neutral, while ばかりか can emphasize a striking addition. はもちろん presents X as obvious, whereas はおろか commonly occurs with negation and adds a more basic Y that is also ruled out.