Translation guide
The English word 'giant' can be a noun meaning a huge mythical creature or a very large person/thing, or an adjective meaning extremely large. Japanese uses different words depending on whether you mean a mythical giant, a large person, or something of enormous size.
A huge human-like creature from myths and fairy tales
The standard word for a mythical giant. Also used figuratively for a very large person.
その巨人は山のように大きかった。
The giant was as big as a mountain.
Literally 'big man', often used in folktales for a giant or a very large, strong man.
昔話に大男が出てきた。
A giant appeared in the old tale.
A person, animal, or object that is unusually large
Can be used metaphorically for a person of great stature or influence, or a very large thing.
彼はバスケットボール界の巨人だ。
He is a giant in the world of basketball.
A phrase meaning 'a huge thing', used for objects or creatures of enormous size.
その動物は巨大なものだった。
That animal was a giant.
Describing something as enormous in size, scale, or degree
The most common adjective meaning 'giant' or 'huge'. Used for physical size, scale, or impact.
巨大なビルが建っている。
A giant building is standing.
巨大な影響を与えた。
It had a giant impact.
Means 'extra-large' or 'giant-sized', often used for products or portions.
特大のピザを注文した。
I ordered a giant pizza.
Casual adjective meaning 'huge' or 'giant'. Common in everyday speech.
でかいクモがいた！
There was a giant spider!
Very casual, emphatic way to say 'ridiculously huge'. Often used for comedic effect.
巨人 is a noun meaning 'giant' (mythical or figurative). 巨大な is an adjective meaning 'giant' or 'huge'. Do not use 巨人 as an adjective.
巨人が現れた。
A giant appeared.
巨大な足跡を見つけた。
We found giant footprints.
The loanword ジャイアント is mainly used in proper nouns (e.g., ジャイアンツ baseball team) or specific product names. It is not a natural way to say 'giant' in general Japanese.
ばかでかいハンバーガーを食べた。
I ate a giant hamburger.