What it means
かける attaches to a verb’s masu-stem and expresses an action that has just begun but is still unfinished, or something that is just about to happen. The exact sense depends on context: with an ongoing action, it highlights partial completion, while with an imminent event, it means the event is on the verge of starting. It conjugates as a regular verb, so its tense and politeness can change.
Usage note
かける in this pattern should not be confused with the ordinary verb meaning “to hang,” “to call,” or “to spend.” The surrounding context is important because the same form can describe either an unfinished action or an imminent event.
How to use it
彼は手紙を書きかけましたが、電話に出ました。
He started writing a letter, but answered the phone.
彼は手紙を書きかけたが、電話に出た。
He started writing a letter, but answered the phone.
Example sentences
図書館で借りた小説を読みかけたまま、電車を降りてしまった。
I got off the train while I had only just begun reading the novel I borrowed from the library.
夕食を作りかけたところで、宅配便が届いた。
Just as I had started making dinner, a delivery arrived.
春になって、庭のチューリップが咲きかけている。
Now that spring has arrived, the tulips in the garden are just about to bloom.