fixed time; regular time; scheduled time
Refers to a predetermined or regular point in time, such as a meeting time, departure time, or scheduled hour.
The meeting starts at the scheduled time.
The bus departed on time.
fixed period; scheduled period
Used for a predetermined or regular interval, such as a fixed term or scheduled duration. Often seen in compound terms like 定時制 (part-time/fixed-time school system).
This course is offered on a fixed-time schedule.
The meeting started at the scheduled time.
The buses on this route run strictly on schedule.
He leaves work on time every day.
随時 means 'at any time, whenever needed,' the opposite of 定時, which specifies a fixed, predetermined time.
フレックス lets employees choose their own start and end times, while 定時 refers to a fixed, company-set work schedule.
Compound of 定 (fixed, determined) and 時 (time). The meaning is transparent from its components.