How to say "gigantic" in Japanese

• 巨大きょだいJLPT N3approx.Common
  na-adjective, nounThe straightforward way to say something is gigantic: it states enormous size directly, fitting a huge building, a vast organization, or anything whose immensity is the point.
  巨大きょだいなタンカーがついに今し方いましがた出港しゅっこうした。↗

  The huge tanker has just left the dock.
• マンモスCommon
  noun (prefix)This is the prehistoric animal's name turned figurative: like English "mammoth", it stresses overwhelming scale, suiting vivid descriptions of a very large facility or enterprise.
  わたしたちの会社かいしゃはマンモス会社かいしゃで、繁雑はんざつな面めんを少すくなくし能率のうりつを上あげるために、改正かいせいあるいは撤廃てっぱいすべき規則きそくとか規約きやくがいくつかある。↗

  Our firm is a giant one, and there are some rules and regulations, which should be revised or rescinded to reduce red tape and increase efficiency.

Both describe enormous size; choose 巨大 for plain, direct statements that something is gigantic, and 「マンモス」 when you want the vivid, figurative flavor of English "mammoth" stressing overwhelming scale.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 巨大きょだいhuge
• どでかいhuge
• ガタイがいいbig and brawny
• がたいのいいbig and brawny
• 魁偉かいいbrawny
• マンモスgigantic