early 14c., "any sentient living creature" (including humans), from Latin animale "living being, being which breathes," noun use of neuter of animalis (adj.) "animate, living; of the air," from anima "breath, soul; a current of air" (from PIE root *ane- "to breathe;" for sense development, compare deer).

A rare word in English before c. 1600, and not in KJV (1611). Commonly only of non-human creatures. It drove out the older beast in common usage. Used derisively of brutish humans (in which the "animal," or non-rational, non-spiritual nature is ascendant) from 1580s.

Quid est homo? A dedlych best and resonable, animal racionale. ["Battlefield Grammar," c. 1450]

The animals in Paradise are the prophet Saleh's camel, the ram which Abraham sacrificed instead of Isaac, Moses's cow, (the red cow, whose ashes were mingled with the water of purification), Soloman's ant (who, when all creatures, in token of their obedience to him, brought him presents, dragged before him a locust, and was therefore preferred before all others because it had brought a creature so much bigger than itself); the queen of Sheba's parrot, who carried messages between her and Solomon ; Ezra's ass ; Jonah's whale ; Kitmer, the dog of the Seven Sleepers, and Mahommed's camel. [Southey, "Omniana," citing Thevenot's Travels into the Levant; for the list, see chapter XXXI]

Old English deor "wild animal, beast, any wild quadruped," in early Middle English also used of ants and fish, from Proto-Germanic *deuzam, the general Germanic word for "animal" (as opposed to man), but often restricted to "wild animal" (source also of Old Frisian diar, Dutch dier, Old Norse dyr, Old High German tior, German Tier "animal," Gothic dius "wild animal," also see reindeer).

This is perhaps from PIE *dheusom "creature that breathes," from root *dheu- (1) "cloud, breath" (source also of Lithuanian dusti "gasp," dvėsti "gasp, perish;" Old Church Slavonic dychati "breathe"). For possible prehistoric sense development, compare Latin animal from anima "breath").

The sense specialization to a specific animal began in Old English (the usual Old English word for what we now call a deer was heorot; see hart), was common by 15c., and is now complete. It happened probably via hunting, deer being the favorite animal of the chase (compare Sanskrit mrga- "wild animal," used especially for "deer"). 

Deer-lick "salty spot where deer come to lick," is attested by 1778, in an American context. The deer-mouse (1840) is so called for its agility.

c. 1200, "brutish, sensual, debased;" late 14c., "in the manner of a beast," from beast + -ly (1). It weakened in British upper crust use to "awfully, exceedingly" by mid-19c. Beastly drunk is from 1794.

Beastly expresses that which is altogether unworthy of a man, especially that which is filthy and disgusting in conduct or manner of life. Bestial is applied chiefly to that which is carnal, sensual, lascivious: as, bestial vices or appetites. [Century Dictionary]

late 14c., "belonging to a beast," c. 1400, "having the qualities of a beast," from Old French bestial (13c.) "relating to animals; beast-like, stupid, foolish, brutal" and directly from Latin bestialis "like a beast," from bestia (see beast).

The sense of "below the dignity of a human" in English is from c. 1400, and often is unjust to beasts. When the beast of the Book of Revelation was meant, the adjectival form bestian (1650s) sometimes was used.

"medieval treatise on beasts" usually with moralistic overtones, 1818, from Medieval Latin bestiarium "a menagerie," also "a book about animals," from bestia (see beast).

A Latin term for such works was liber de bestiis compositus. Roman bestiarius meant "a fighter against beasts in the public entertainments." Bestiarian (1882), modeled on humanitarian, was a word for "one who advocates kind treatment of animals," especially "anti-vivisectionist," but earlier bestiarianism (1864) had been used as the opposite of humanitarianism in reference to cruel and brutal policies.

"person or thing regarded with especial aversion," 1844, from French bête noire, literally "the black beast." For bête see beast; noire is from Latin niger (see Negro).

1781, from Afrikaans, from Dutch hertebeest "antelope," from hert "hart" (see hart) + beest "beast, ox" (in South African Dutch "steer, cattle"), from Middle Dutch beeste, from Old French beste "beast" (see beast).

1838, from South African Dutch (in modern Afrikaans wildebees, plural wildebeeste), literally "wild beast," from Dutch wild "wild" (see wild (adj.)) + beest "beast, ox" (in South African Dutch "steer, cattle"), from Middle Dutch beeste, from Old French beste "beast" (see beast).