1.
going, outward journey
The journey toward a destination, as opposed to the return trip.
行きは電車で、帰りはバスで行った。
I went by train and came back by bus.
行き帰りで2時間かかる。
It takes 2 hours round trip.
行き帰り = round trip, there and back
行きは天気がよかったが、帰りは雨になった。
The weather was nice on the way there, but it rained on the way back.
2.
bound for
Used as a suffix on signs and announcements to indicate destination.
東京行きの新幹線に乗る。
To take the shinkansen bound for Tokyo.
～行き as suffix means 'bound for'
大阪行きのバスは何番ですか。
What number is the bus bound for Osaka?
空港行きのリムジンバスは30分おきに出ている。
The limousine bus bound for the airport departs every 30 minutes.
行き is a noun derived from 行く (to go), meaning the outward journey.
COMMON PATTERNS:
- 行きと帰り (going and returning)
- 行き帰り (round trip)
- ～行き (bound for ~)
AS SUFFIX:
- 東京行き (Tokyo-bound)
- 成田空港行き (bound for Narita Airport)
- 上り/下り (up/down trains, alternative for direction)
ANTONYM:
- 帰り (return, way home)