ていく details
write + (and…) + change onward from now
kaite iku
change onward from now; do and go
meaning: go on writing
秋になると、日がどんどん短くなっていく。
aki ni naru to, hi ga dondon mijikaku natte iku.
When autumn comes, the days steadily go on getting shorter. neutral
傘、持ってった方がいいよ。
kasa, mottetta hou ga ii yo.
You'd better take an umbrella. casual
- contraction
- past
- polite
Examples
change continuing onward — a development moving away from the present point
秋になると、日がどんどん短くなっていく。
aki ni naru to, hi ga dondon mijikaku natteiku.
When autumn comes, the days steadily go on getting shorter. neutral
高齢化により、町の人口は今後も減っていくと考えられます。
koureika ni yori, machi no jinkou wa kongo mo hette iku to kangaeraremasu.
With the aging of society, the town's population is expected to keep declining. formal
do and go — perform the action and move away, or carry something along
傘、持ってった方がいいよ。
kasa, mottetta hou ga ii yo.
You'd better take an umbrella. casual
父は毎朝、駅まで歩いていきます。
chichi wa maiasa, eki made aruite ikimasu.
My father walks to the station every morning. neutral
Formation
{V-te}いくattaches to て-form
Variant notes
- てく — い drops in casual speech — 持ってく; past 持ってった. Speech and informal writing only.
Notes
Related patterns
Similar
Both stretch an event through time — 変わり続ける presents one unbroken or steadily repeated course, while 変わっていく tracks a drift that tolerates gaps and adds a direction away from now that 続ける lacks.
Opposite
- てくるplain-antonym
The same aspectual machinery pointed opposite ways — ていく tracks change or motion heading away from the speaker's here-and-now (減っていく), てくる tracks it arriving at the here-and-now (減ってきた); deictic direction is the entire difference.
Lookalikes
One form apart on the same verb — 買いに行く states why you are going (purpose, masu-stem＋に), 買っていく says you buy and then move on or take it along (sequence, て-form); the stem choice, not 行く, carries the meaning.
Casual speech collapses them to a one-mora difference — 買っとく "buy in advance" vs 買ってく "buy and go"; only context tells a listener which auxiliary just went by.