ていく
- 1A change or process that continues or progresses gradually from the present into the future.Ex. 1
- 2Ongoing growth or development that keeps advancing, often with adverbs like どんどん or ますます.Ex. 2
- 3Doing an action and then leaving, or an action moving away from the speaker.
Spelling: いく is usually written in hiragana in this auxiliary use
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Used in both speech and writing to describe trends, growth and changes that extend forward in time. It often appears with adverbs of gradual change such as ますます, どんどん and だんだん. Compared with てくる, which views change up to the present, ていく looks from the present onward into the future.
Learners often mix up ていく and てくる; ていく points forward from now, while てくる points toward the present.
Note that in the change sense, いく is normally written in hiragana rather than as the kanji 行く.
Do not use plain ている when you want to express that a change will keep progressing into the future.
- てくるN4「てくる」 points in the opposite direction: a change gradually progresses up to the reference point (usually the moment of speaking), or an action comes toward the speaker, or someone goes to do something and comes back. The difference from 「ていく」 is direction, not simply past vs. future—「これから寒くなってくる」 is also valid.
- つつあるN2「つつある」 attaches to the ます-stem and is mostly used in written language; it only indicates that a change is in progress and not yet complete, focusing on the current process rather than continuation from now into the future, and it has no spatial-movement usage.
- 一方だN3「一方だ」 is close to 「ていく」 only in the sense of gradual change; it attaches to dictionary form and emphasizes moving in one direction with no sign of improvement, often used for negative trends with a nuance of concern. 「ていく」 attaches to the て-form, works for both good and bad changes, and can also express spatial movement.
- ようになるN4「ようになる」 describes a change in ability or habit, often using 「ようになった」 for the new state that has already formed; 「ていく」 describes a process developing step by step from now into the future, and can also express moving away in space. They cannot be directly interchanged.
- ているN5「ている」 expresses ongoing action, resulting state, or habitual repetition; 「ていく」 carries direction, indicating development from now into the future or movement away from the speaker. For example, 「変わっている」 means it has already changed, while 「変わっていく」 means it will keep changing—they cannot be interchanged.
Unlike てくる (change leading up to now), ていく views change from now onward, while ている simply marks an ongoing action or state with no direction. つつある is more formal and stresses a change currently underway, 一方だ stresses a one-way (often negative) trend, and ようになる focuses on the resulting new state or ability rather than the ongoing progression.
