要塞|ようさいyousai[0]heiban (flat)

1. nounfort; stronghold; fortification
   そこでまだ要塞ようさい都市としの遺跡いせきをみることができる。↗

   You can still see the remains of the fortress there.

• Synonym砦とりでNeutralA fort or stronghold with an old-fashioned feel; smaller in scale than 「要塞」. Also used figuratively for one's last line of defense.
• Synonym城塞じょうさいWrittenA written-style word for a castle fortress; stresses a defensive building surrounded by walls.
• Synonym堡塁ほうるいWrittenA written, military-flavored word for a fortified position or works; less common than 「要塞」.
• Synonym防塞ぼうさいWrittenA rare written word for a defensive fort or barricade.
• Synonym要害ようがいWrittenRefers to defensible, strategically important terrain, as in 「天然の要害」; the focus is on the land, not the building.
• Related城郭じょうかくWrittenA historical, written-style word for a castle and its surrounding walls; stresses the structure of a castle compound.
• Related塁るいNeutralThe same word as the 「砦」 above; 「塁」 and 「寨」 are merely alternative spellings, not separate synonyms.
• Related城しろNeutralThe everyday word for a castle, as in 「大阪城」 or 「ヨーロッパの城」; it does not specifically mean a military fortress.
• Related堅塁けんるいWrittenA written word for a strongly fortified stronghold; also used figuratively for a hard-to-crack opponent.

Use 「要塞」 for modern military fortifications, as in 「要塞都市」. For old-style forts say 「砦」, for castles 「城」, for defensible terrain 「要害」, and for castle structures 「城郭」. The other written-style terms are rarer alternatives.

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

1. 外敵がいてきから防御ぼうぎょするために、国境こっきょう・海岸かいがんなど戦略的せんりゃくてきに重要じゅうような場所ばしょに作つくった建造物けんぞうぶつ、軍事ぐんじ施設しせつ。とりで。