Giant
Middle English geant (with the first syllable later influenced by Latin gigant- ), from Old French, via Latin from Greek gigas, gigant- .
wiktionary
From Middle English geaunt, geant, from Old French geant, gaiant (Modern French géant) from Vulgar Latin *gagās, gagant-, from Latin gigās, gigant-, from Ancient Greek γίγας(gígas, “giant”) Cognate to giga-(“1,000,000,000”).
Displaced native Middle English eten, ettin (from Old English ēoten), and Middle English eont (from Old English ent).
Compare Modern English ent(“giant tree-man”) and Old English þyrs(“giant, monster, demon”).
etymonline
giant (n.)
c. 1300, "fabulous man-like creature of enormous size," from Old French geant, earlier jaiant "giant, ogre" (12c.), from Vulgar Latin *gagantem (nominative gagas), from Latin gigas "a giant," from Greek Gigas (usually in plural, Gigantes), one of a race of divine but savage and monstrous beings (personifying destructive natural forces), sons of Gaia and Uranus, eventually destroyed by the gods. The word is of unknown origin, probably from a pre-Greek language. Derivation from gegenes "earth-born" is considered untenable.
In þat tyme wer here non hauntes Of no men bot of geauntes. [Wace's Chronicle, c. 1330]
It replaced Old English ent, eoten, also gigant (from Latin). The Greek word was used in Septuagint to refer to men of great size and strength, hence the expanded use in modern languages; in English of very tall and unusually large persons from 1550s; of persons who have any quality in extraordinary degree from 1530s. As a class of stars, from 1912. As an adjective from early 15c. Giant-killer is from 1726.
