〜かける／〜かけの
Half-done, left unfinished midwaymachine translation
FormationVerb ます-form (drop ます) + かける・かけだ・かけの + noun
〜かける attaches to a verb to describe an action that has begun but is still unfinished: 読みかけの本 (a half-read book), 飲みかけのコーヒー (a half-drunk coffee). The form 〜かけの + noun describes an object in a half-finished state, while 〜かけだ ends a sentence: この手紙は書きかけだ.
かける also means "just about to, on the verge of": 言いかけてやめた (started to say something, then stopped), 死にかけた (nearly died). In this sense the action has only just begun, or hasn't yet taken shape.
Place かける alongside the patterns for stages of an action: 〜はじめる (N4) is starting and continuing, 〜きる is doing something 100% completely, while かける stops midway — begun but not finished. Because it carries a built-in sense of "incomplete," かけ very often pairs with まま: やりかけたまま寝てしまった (left it half-done and fell asleep).
Examples
机の上に読みかけの本が置いてあります。
There's a half-read book lying on the desk.
宿題をやりかけたまま、寝てしまった。
I left my homework half-done and fell asleep.
彼は何か言いかけて、やめてしまった。
He started to say something, then stopped.