The Japanese word for hour is
時

じ - ji

Japanese Definition

時
1. n. time
時の流れ - the flow of time
2. n. an event, case, occasion, moment; a specific period in time
困った時は私に相談してください。 - Please consult with me when troubled (in times of trouble).
3. n. a time of something
4. n. a season
5. n. a tense
6. n. (literary) the time during which a narrative takes place
時は冬 - It was winter, ...
7. suffix. time of..., time for...
8. counter. hour, o’clock
時計を見ると、ちょうど１２%時３４%分５６%秒だった。 - When I looked at the clock, it was just 12:34 and 56 seconds.
9. suffix. at the time of...
10. affix. time, moment
11. affix. at that time, chance, occasion
12. affix. hour, hourly
13. n. (obsolete) (only used in, ja, 時過ぐ, tr=sada sugu): to pass through the prime of life, grow old

時間
1. n. time
時間はありますか？ - Do you have any time?
時間はいつでも大丈夫です。 - literally As for time, whenever is fine.
もうこんな時間！ - literally it's already this sort of time!
時間にルーズ - literally lax about time
時間と空間の関係 - the relationship between time and space
2. n. hour
1%時間は 60%分です。 - One hour is 60 minutes.
3. n. the hours or time when something happens
試験時間に遅れた - literally late to the time of the exam
営業時間は月火水、午前９%時から午後２%時までです。 - Business hours are Monday to Wednesday, 9 AM to 2 PM.
開館時間 - hours of operation
時間です！ - literally It's time!
閉園の時間です！ - literally It's time for our closing!
あまり時間がなくてすみません - sorry for not having the time to do something
4. n. Usage: The more general word for time, as in "when something happens", is 時.
Usage: * 海辺に行った時 - the time I went to the beach, when I went to the beach
5. counter. an hour-long period
一時間、二時間、五時間半 - one hour, two hours, five and a half hours
何時間もかかりそうです。 - Apparently it will take many hours.
6. n. (dialect Ibaraki) time
7. n. (dialect Ibaraki) hour
8. n. (dialect Ibaraki) the hours or time when something happens
9. counter. (dialect Ibaraki) an hour-long period