1To go; to move or travel toward a destination. Indicates motion away from the speaker's location, in contrast to 来る (to come). The most basic, everyday use of the word.
明日は友達と映画を見に行きます。
Tomorrow I'm going to see a movie with a friend.
夏休みに沖縄へ行きたい。
I want to go to Okinawa during summer vacation.
もう寝る時間だから、お風呂に行ってきなさい。
It's bedtime, so go take a bath.
この電車は新宿には行きません。
This train doesn't go to Shinjuku.
2To move along or travel through (a road, path, route); to walk along. Focuses on the route itself rather than the destination, and has a slightly literary, descriptive feel; often read as ゆく in this sense.
細い山道を一人で行くのは少し怖かった。
Walking the narrow mountain path alone was a little scary.
川に沿ってゆけば、やがて湖に出る。
If you follow along the river, you'll eventually come out at a lake.
3To proceed; to turn out (well, badly, etc.); to go (a certain way). Very common in expressions about how things are progressing — especially うまくいく (to go well). Usually written in kana in this sense.
面接はうまくいったと思う。
I think the interview went well.
新しい仕事はうまくいっていますか。
Is the new job going well?
話し合いがうまくいかなくて、みんな疲れている。
The discussions aren't going well and everyone is exhausted.
4To go with (a particular choice or approach); to decide on a way. Used as 〜で行く to express choosing a direction or strategy — very common in conversation.
今日の昼ごはんはラーメンで行こう。
Let's go with ramen for lunch today.
プレゼンはこの案で行きます。
We'll go with this proposal for the presentation.
今回はシンプルなデザインで行きたい。
This time I'd like to go with a simple design.
5To pass (of time, seasons); to go by. Usually read ゆく, with a literary or poetic feel. Survives mostly in set phrases like ゆく年くる年 (the year passing, the year coming) and 過ぎゆく.
ゆく年くる年、今年もいろいろなことがあった。
As one year passes and another comes, many things happened this year too.
時はゆき、あの頃の子どもたちはもう大人になった。
Time passed, and the children of those days have already grown up.
6To flow or stream (of blood, current, wind, etc.); to move in a given direction. A somewhat figurative use, often describing blood, electricity, or air moving through something.
緊張すると顔に血が行く感じがする。
When I get nervous, I feel blood rushing to my face.
7To pass away; to die. Almost always written 逝く; gentler and more respectful than 死ぬ, common in formal contexts and obituaries.
祖父は昨年の春、静かに逝きました。
My grandfather peacefully passed away last spring.
彼女は若くしてこの世を逝った。
She left this world at a young age.
8To reach (a stage, extent, age, etc.); to get to a certain point. Used as 〜まで行く or そこまで行く to express reaching a level or range.
話がそこまで行くとは思わなかった。
I didn't expect the conversation to get to that point.
値段が一万円まで行くと、ちょっと買いにくい。
Once the price gets up to ten thousand yen, it's a bit hard to buy.
9To reach or arrive (of information, instructions, news, etc.); to be delivered. Used in phrases like 連絡が行く (to be contacted) to express that something has reached someone.
後ほど担当者から連絡が行きます。
Someone in charge will contact you later.
お知らせはもう全員のところに行きましたか。
Has the notice reached everyone yet?
10Auxiliary verb attached to the -te form of another verb to indicate that an action or state continues or progresses away from the present — outward in space or onward in time. Paired with 〜てくる (movement toward the speaker / up to the present), 〜ていく describes change continuing into the future. Usually written in kana, and in casual speech the い is often dropped: やってく for やっていく.
これからも日本語の勉強を続けていきたい。
I want to keep studying Japanese from now on.
世の中は少しずつ変わっていく。
The world changes little by little.
桜の花が風に散っていった。
The cherry blossoms scattered away in the wind.
もう遅いから先に帰ってくね。
It's getting late, so I'll head home first (casual, shortened from 帰っていく).
11Slang for reaching orgasm; to come/cum. Usually written in katakana as イク/イッた, and is explicit — context-sensitive.
彼女はもうイッたらしい。
It seems she already came.
12Slang for being high or tripping — a drug-induced altered state of consciousness. Close in nuance to 'getting high', usually written in katakana as イク/イッてる.
あいつ完全にイッてる目をしている。
That guy's got completely tripped-out eyes.