quadra
四角形
解説 Definition
四つの辺と四つの角を持つ幾何学的図形。正方形または一般的な四角形を指す。
A quadra is a square or four-sided geometric form, and the term may also describe a square-shaped area such as a plaza or city block. In standard English geometry, quadrilateral is the more usual general term for any figure with four sides.
覚え方のコツ Memory Tip
quadra はラテン語で「四角・正方形」を表す形に由来し、quadrangle、quadrilateral、quadrant と共通する quadr-「4」を手掛かりにする。例文では a quadra や quadra-shaped plaza として、四辺と四つの角を持つ図形・広場を指す。ただし一般的な英語の幾何用語は quadrilateral である。
Focus on the element quadr-, meaning “four,” which also appears in quadrilateral, quadrangle, and quadrant. This makes the intended image straightforward: a form bounded by four sides and four corners. In the examples, quadra can stand alone as a noun or appear in quadra-shaped plaza to describe a square or four-sided layout. However, learners should remember that quadrilateral is the standard general English term in geometry, while quadra is uncommon and may occur in specialized, borrowed, or naming contexts. Use the shared quadr- element as the reliable memory anchor.
例文
The architect designed a quadra-shaped plaza.
建築家は四角形の広場を設計した。
In geometry class, we studied the properties of a quadra.
幾何学の授業で、四角形の性質について学んだ。
The quadra fits perfectly in the center of the city.
その四角形の広場は街の中心にぴったり収まる。
quadra の類義語・関連語
quadra の語源・成り立ち Etymology
ラテン語 quadra（四角、正方形）から。語根 quadr- は「4」を意味し、quadrangle（四角形）や quadrilateral（四辺形）と同根。4つの辺で囲まれた形という原義がそのまま「四角形」の意味になった。
Quadra comes from Latin quadra, referring to a square, a rectangular object, or something arranged in four parts. It contains the Indo-European numerical element seen in Latin quattuor, “four,” and in English formations beginning with quadr-. The same element appears in quadrangle, quadrilateral, quadrant, and quadruple. Its geometric application follows directly from the idea of a shape organized around four sides, corners, or divisions.
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