1. The process of maintaining constant temperature, humidity, and other environmental factors for the purpose of allowing an embryo to develop properly within an egg, a prematurely-born infant to continue its development outside of its mother's womb, or microbe or tissue cultures to grow until they are a scientifically or medically useful size. When done artificially, incubation is done within an incubator.
   
   
2. The period between the initial infection of a host by a microbe and the time that symptoms of disease begin.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

I managed to obtain the use of a room in the temple and took constant part in her services... Not a single night did I pass, nor even doze off during the day, without some vision of her.
-- Apuleius, Metamorphoses XI.

In Latin, the verb incubo means "to lie upon." Like the English word derived from it, incubatio was often used to refer to a mother hen brooding over her eggs. It could also be used as a metaphor for a thief hoarding treasure, the bereaved hurling himself upon the ground at a funeral, or a country bordering the sea.

But the word grew to develop a specialized meaning in Roman religion, and it is in this sense that the word incubation is used by historians. To incubate meant to sleep in a temple in the hope that a god would appear in a dream.

Incubation was most strongly associated with the god Asclepius (or Aesculapius), who was believed to heal sick vistors who slept in his temples. Those who fell asleep near his altar would usually receive instructions in a dream about how to treat their illness, though sometimes they would simply wake up cured. (In one case, a man with an ulcer dreamt that the god himself performed surgery upon him; when he woke up, he said, the floor of the temple was covered in blood.)

The temples of Isis and Serapis were also popular sites for incubation. Hundreds of inscriptions survive, thanking the gods for the blessings and insights they granted their worshippers in dreams.

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In`cu*ba"tion (?), n. [L. incubatio: cf. F. incubation.]

1.

A sitting on eggs for the purpose of hatching young; a brooding on, or keeping warm, (eggs) to develop the life within, by any process.

Ray.

2. Med.

The development of a disease from its causes, or its period of incubation. (See below.)

3.

A sleeping in a consecrated place for the purpose of dreaming oracular dreams.

Tylor.

Period of incubation, ∨ Stage of incubation Med., the period which elapses between exposure to the causes of a disease and the attack resulting from it; the time of development of the supposed germs or spores.<-- for infectious diseases -->

© Webster 1913.