animal

Etymology 1

From Middle English animal, from Old French animal, from Latin animal, a nominal use of an adjective from animale, neuter of animālis, from anima (“breath, spirit”). Displaced native Middle English deor, der (“animal”) (from Old English dēor (“animal”)), Middle English reother (“animal, neat”) (from Old English hrīþer, hrȳþer (“neat, ox”)).

noun

1. (sciences) A eukaryote of the clade Animalia; a multicellular organism that is usually mobile, whose cells are not encased in a rigid cell wall (distinguishing it from plants and fungi) and which derives energy solely from the consumption of other organisms (distinguishing it from plants).
   A cat is an animal, not a plant. Humans are also animals, under the scientific definition, as we are not plants.
2. (strictly) Any member of the kingdom Animalia other than a human.
3. (colloquial) Any land-living vertebrate (i.e. not fishes, insects, etc.).
   Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame. With more settled people, animals were harnessed to capstans or caged in treadmills to turn grist into meal. 2013 July-August, Henry Petroski, “Geothermal Energy”, in American Scientist, volume 101, number 4
4. (figurative) A person who behaves wildly; a bestial, brutal, brutish, cruel, or inhuman person.
   My students are animals.
   Own me, I'll let you play the role I'll be your animal 2019, “Bad Guy”, Finneas O'Connell, Billie Eilish O'Connell (lyrics), performed by Billie Eilish
5. (informal) A person of a particular type.
   He's a political animal.
6. Matter, thing.
   a whole different animal
   no such animal

Etymology 2

From Latin animālis, from either anima (“breath, spirit”) or animus. Originally distinct from the noun, it became associated with attributive use of the noun and is now indistinguishable from it.

adj

1. Of or relating to animals.
   animal instincts
2. Raw, base, unhindered by social codes.
   animal passions
3. Pertaining to the spirit or soul; relating to sensation or innervation.
   To explain what activated the flesh, ‘animal spirits’ were posited, superfine fluids which shuttled between the mind and the vitals, conveying messages and motion. 2003, Roy Porter, Flesh in the Age of Reason, Penguin, published 2004, page 47
4. (slang, Ireland) Excellent