1.
at any time; as needed; whenever necessary
Indicates that something can be done at any time without a fixed schedule, or that something is done on an as-needed basis. Composed of 随 (follow, as one pleases) + 時 (time). Common in formal announcements, business communications, and official notices.
Usage
随時 is a formal word commonly seen in business emails, official announcements, and signs. It implies flexibility — there is no fixed time or schedule, and the action happens as the situation requires.