定数

• Reading: ていすう
• Romaji: teisū
• Kanji breakdown: 定 (tei/sada-) — fixed, established; 数 (sū/kazu) — number, quantity
• Pronunciation: /te.i.sɯː/

Meaning

Constant; a fixed numerical value that does not change within a given context, mathematical expression, or physical law.

A noun used across mathematics, physics, and programming. In physics, fundamental constants such as the speed of light (c), Planck's constant (h), and the gravitational constant (G) are called 物理定数. In algebra, a constant is contrasted with a variable (変数). In programming, 定数 (or 定数値) refers to an immutable value declared in code.

Examples

1. プランク定数は量子力学において最も基本的な物理定数の一つだ。 Planck's constant is one of the most fundamental physical constants in quantum mechanics.
2. この微分方程式を解くと積分定数が生じるため、初期条件で値を決定する。 Solving this differential equation produces a constant of integration, whose value is determined by the initial conditions.
3. 万有引力定数Gの精密な測定は現代物理学の重要な課題の一つだ。 The precise measurement of the gravitational constant G is one of the important challenges in modern physics.

Usage Guide

Context: mathematics, physics, programming, engineering

Tone: neutral

Origin & History

Compound of 定 (tei — fixed, settled) and 数 (sū — number). Together they form a straightforward description of a number that is determined and does not vary.

Cultural Context

Era: Modern

Generation: Students and professionals

Social background: Technical