塁|るいrui[1]atamadaka (head-high)

1. noun, baseballbase; bag; sack
2. nounfortress; stronghold

• Related砦とりでNeutralNeutral native-Japanese word for a fort or stronghold, stressing holding a position; often figurative for a last line of defense.
• Related要塞ようさいNeutralNeutral, modern word for a military fortress, stressing solid defensive installations.
• Related城郭じょうかくWrittenWritten term for a castle with its walls and outer defenses, stressing the castle's overall defensive structure.
• Related城しろNeutralThe everyday, most common word for a castle; it does not refer to a base.
• Related城塞じょうさいWrittenWritten/formal term for a castle fortress, taking in the whole castle defense; 「塁」 today mostly means a baseball base, or an earthen defensive work.
• Related堡塁ほうるいWrittenWritten word for a fort or fortification of earth, stone or concrete; it does not mean a baseball base.
• Related防塞ぼうさいWrittenWritten and rare: a defensive position, stressing the holding of a line.
• Related城塁じょうるいWrittenWritten and rare: a castle fortress, stressing the defensive works of the castle.
• Related防塁ぼうるいWrittenWritten word for earthen ramparts or defensive walls, as in 「元寇防塁」, stressing earth-and-stone construction.
• Related要害ようがいWrittenWritten word for a strategic or naturally strong spot, stressing the location, as in 「天然の要害」.
• Related柵きWrittenArchaic word for an ancient palisade fortress; rare and not used in modern Japanese.

Use 「塁」 for a baseball base or an earthen defensive work, as in 「二塁打」 and 「塁に出る」. For a castle say 「城」; for a fortress, 「要塞」 or 「砦」; for a strategic spot, 「要害」. The remaining written terms are rare or specialized.

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

1. （ルイ）ベース。