rarefaction
(noun) a decrease in the density of something; “a sound wave causes periodic rarefactions in its medium”
Source: WordNet® 3.1
rarefaction (countable and uncountable, plural rarefactions)
A reduction in the density of a material, especially that of a fluid.
• compression
Source: Wiktionary
Rar`e*fac"tion, n. Etym: [Cf. F. raréfaction. See Rarefy.]
Definition: The act or process of rarefying; the state of being rarefied; - - opposed to condensation; as, the rarefaction of air.
Source: Webster’s Unabridged Dictionary 1913 Edition
19 November 2024
(noun) bushy plant of Old World salt marshes and sea beaches having prickly leaves; burned to produce a crude soda ash
Coffee dates back to the 9th century. Goat herders in Ethiopia noticed their goats seem to be “dancing” after eating berries from a particular shrub. They reported it to the local monastery, and a monk made a drink out of it. The monk found out he felt energized and kept him awake at night. That’s how the first coffee drink was born.
