liquid

Etymology

From Middle English liquide, from Old French liquide, from Latin liquidus (“fluid, liquid, moist”), from liqueō (“to be liquid, be fluid”), ultimately from Proto-Indo-European *wleykʷ- (“to flow, run”). Doublet of liquidus. As a term for a consonant, it comes from Latin liquida (cōnsōnāns), a calque of Ancient Greek ὑγρὸν (σύμφωνον) (hugròn (súmphōnon), “liquid consonant”).

noun

1. A substance that is flowing, and keeping no shape, such as water; a substance of which the molecules, while not tending to separate from one another like those of a gas, readily change their relative position, and which therefore retains no definite shape, except that determined by the containing receptacle; an inelastic fluid.
   A liquid can freeze to become a solid or evaporate into a gas.
   The dawn of the oil age was fairly recent. Although the stuff was used to waterproof boats in the Middle East 6,000 years ago, extracting it in earnest began only in 1859 after an oil strike in Pennsylvania.[…]It was used to make kerosene, the main fuel for artificial lighting after overfishing led to a shortage of whale blubber. Other liquids produced in the refining process, too unstable or smoky for lamplight, were burned or dumped. 2013-08-03, “Yesterday’s fuel”, in The Economist, volume 408, number 8847
2. (phonetics) Any of a class of consonant sounds that includes l and r.
   Many female forenames are regarded as euphonyms. What is and is not euphonious is necessarily subjective, but it could be suggested that names containing labials (b, m), sibilants (s, sh) and liquids (l, r) are more likely to be euphonyms than those that do not. 1996, Adrian Room, An Alphabetical Guide to the Language of Name Studies, page 41
   […]-able does not attach to verbs ending in a postconsonantal liquid […] 1999, Ingo Plag, Morphological Productivity, page 86

adj

1. Flowing freely like water; fluid; not solid and not gaseous; composed of particles that move freely among each other on the slightest pressure.
   liquid nitrogen
2. (finance, of an asset) Easily sold or disposed of without losing value.
3. (finance, of a market) Having sufficient trading activity to make buying or selling easy.
4. Flowing or sounding smoothly or without abrupt transitions or harsh tones.
   a liquid melody
5. (phonology) Belonging to a class of consonants comprised of the laterals and the rhotics, which in many languages behave similarly.
   /l/ and /r/ are liquid consonants.
6. Fluid and transparent.
   the liquid air