1.
diagram; chart (visual representation of data or relationships)
A visual diagram used to illustrate relationships, processes, or data. Used in technical, business, and academic contexts. Often shortened to ダイヤ.
2.
(train) schedule; operating timetable
In the context of railways, buses, and other scheduled transport, refers to the operating schedule — the plan of when each train or bus runs. Usually shortened to ダイヤ in this sense, as in 運行ダイヤ (operating schedule) or ダイヤの乱れ (schedule disruption).
A loanword from English "diagram" that has taken on two distinct uses in Japanese.
Usage
In general contexts, ダイヤグラム refers to any visual diagram or chart — the same meaning as English "diagram." In the world of public transport (especially railways), however, the word has a specialized meaning: the operating schedule itself. This comes from the historical use of graphical time-distance charts to plan train operations. In this transport sense, the word is almost always shortened to ダイヤ.
Common collocations
- ダイヤグラムを描く: to draw a diagram
- ダイヤが乱れる: the train schedule is disrupted
- ダイヤの変更: schedule change
- 運行ダイヤ: operating schedule
- ダイヤ改正: timetable revision (the periodic official schedule update)
Similar words
- 図: figure, diagram — the native Japanese word, broader and more common for visual figures
- 時刻表: timetable — the printed or posted schedule listing departure times, as opposed to ダイヤ which refers to the operating plan itself
- チャート: chart — often used for business or statistical charts (bar chart, pie chart, etc.)