外周|がいしゅうgaishuu[0]heiban (flat)

1. nounouter circumference; perimeter
2. nounoutskirts; periphery

• Synonym外縁がいえんWrittenWritten style and less common; means the outer edge, as in 「銀河の外縁」; 「外周」 can also refer to the length and area of the outer ring.
• Related周囲しゅういNeutralMeans the area around something or its surroundings, and also its circumference, as in 「周囲の目」「池の周囲」; 「外周」 is specifically the outer ring or its length.
• Related周辺しゅうへんNeutralRefers to the surrounding area or neighborhood, as in 「駅周辺」, and is very common in daily use; 「外周」 is the outer ring and carries no sense of the nearby area.
• Related周縁しゅうえんWrittenWritten style, often academic, as in 「社会の周縁」, stressing the fringe or edge zone; 「外周」 is for the outer ring of a concrete object or area.
• Antonym中心ちゅうしんNeutralThe exact middle of a figure or area, extremely common in everyday use; positionally the opposite of 「外周」, which sits at the periphery.
• Antonym内周ないしゅうNeutralThe inner circumference of a round object, the counterpart of the outer-ring 「外周」, as with a track's or a pipe's inner and outer rings.

Use 「外周」 for the outer ring of an object or area or its length, as in 「外周道路」. For the nearby area say 「周辺」, for the surroundings 「周囲」, and for the inner ring 「内周」.

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

1. あるものの外側そとがわの周囲しゅういの長ながさや区域くいき、部分ぶぶん。