atom

The smallest possible amount of matter which still retains its identity as a chemical element, now known to consist of a nucleus surrounded by electrons.

• Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis: the ability to convert water and carbon dioxide into carbohydrates and waste oxygen using solar energy. The evolutionary precursor of photo

A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter.

The smallest, indivisible constituent part or unit of something.

• Towards the following morning, the thermometer fell to 5°; and at daylight, there was not an atom of water to be seen in any direction.
• But at this critical moment the pirate astern sent a mischievous shot and knocked one of the men to atoms at the helm.

In logical atomism, a fundamental fact that cannot be further broken down.

The smallest medieval unit of time, equal to fifteen ninety-fourths of a second.historical

A mote of dust in a sunbeam.

A very small amount; a whit.

• "Doctor, tell me one word more," said Theodore, quivering with suppressed emotion. "How do you think it will end?" / "I have hardly the faintest atom of hope," answered this honest, earnest man.

An individual number or symbol, as opposed to a list; a scalar value.

An integer representing a particular string.

A non-zero member of a partially ordered set that has only zero below it (assuming that the poset has a least element, its "zero").

• In a Venn diagram, an atom is depicted as an area circumscribed by lines but not cut by any line.