A clock with an alarm that can be set to sound at a determined time.

An extremely accurate reference clock whose operation is based on an atomic process, typically the frequency of electromagnetic radiation associated with a specified energy-level transition in an element such as cesium.

(biology) Any of several mechanisms that regulate the periodicity of biological functions. / The progression from puberty to menopause during which a woman can bear children.

All day and night; all of the time.

continuous; incessant; without interruption; all day long, 24 hours per day; nonstop: from the concept that it happens while the hands of the clock go all the way around.

(Britain) A single stem of a dandelion in its post-flowering state with the downy covering of its head intact. The term is applied when the flower is used, or is thought of as suitable for use, in a children's pastime by which the number of puffs needed to blow the filamentous achenes from a dandelion is supposed to tell the time.

An alarm clock that includes a radio; a radio alarm clock

A device that records, on timecards, the times when employees begin and finish work.

A small clock with a carrying handle, originally designed for travelling.

A clock built into a case.