surd
surd — 名詞
1. a number that contains a root symbol (such as √2 or √3) and cannot be simplified
根式；無理根
無法以分數表示之根式，如√2
a number that contains a root symbol (such as √2 or √3) and cannot be simplified to a whole number or a simple fraction; a root that does not produce a rational number.
In algebra class, Leo had to simplify expressions that contained surds like 2√3.
Leo 在代數課上必須簡化含有 2√3 這類根式的算式。
collocation: simplify a surd
The square root of seven is a surd because its decimal form never ends or repeats.
七的平方根是根式，因為它的十進位形式永不終止或重複。
Kenji showed that √5 is a surd, while 0.5 is a rational number written as one half.
Kenji 指出 √5 是根式（無理根），而 0.5 是可以用二分之一表示的有理數。
contrast: surd vs rational number
Mr. Hassan asked the students to identify which numbers on the worksheet were surds.
Hassan 老師要學生辨認學習單上哪些數字是根式。
The exam question required Dario to add two surds and write the answer in simplest form.
考題要求 Dario 將兩個根式相加，並以最簡形式作答。
grammar pattern: add / simplify / multiply a surd
- simplify a surd
- add surds
- multiply surds
- irrational surd
- quadratic surd
- irrational number
broader category — all surds are irrational, but not all irrationals are surds
- radical
common informal term for the root expression itself (e.g. √3)
- rational number
a number expressible as a fraction of two whole numbers
文法句型
a surd
the surd + noun
用法筆記
Often taught alongside rational and irrational numbers in high-school algebra. A surd is always an irrational number, but not every irrational number (such as π) is a surd — surds specifically involve roots.
常見錯誤
2. a speech sound made without vibration of the vocal cords; a consonant such as p,
清音
發音時聲帶不振動的子音
a speech sound made without vibration of the vocal cords; a consonant such as p, t, or k that uses only the breath and not the voice.
Abigail touched her throat and felt no vibration when she said the surd 'p'.
Abigail 在說清音「p」的時候摸摸喉嚨，感覺不到震動。
test: feel throat vibration for voiced vs surd
In phonetics class, Kenji listed the English surds: p, t, k, f, s, and others.
Kenji 在語音學課上列出了英文中的清音：p、t、k、f、s 等。
The difference between 'b' and 'p' is that 'b' is voiced while 'p' is a surd.
「b」和「p」的差別在於「b」是濁音，而「p」是清音。
minimal pair: voiced vs surd contrast
The final sound in 'cats' is a surd, but the 's' in 'dogs' is actually voiced.
「cats」的最後一個音是清音，但「dogs」的「s」其實是濁音。
Rafael could hear the difference between a surd and a voiced sound by holding his ears.
Rafael 靠摀住耳朵就能聽出清音和濁音的差別。
- surd consonant
- surd sound
- produce a surd
- voiceless surd
- voiceless consonant
more common modern term in linguistics
- voiceless sound
general term covering both consonants and vowels
- sonant
a voiced sound produced with vocal cord vibration
- voiced consonant
a consonant like b, d, or g that uses the vocal cords
文法句型
a surd
surd + noun
用法筆記
Common in linguistics and language-teaching contexts. Most English voiceless stops (p, t, k) and fricatives (f, s, ʃ, θ) are surds. The opposite term is 'sonant' (a voiced sound).
常見錯誤
surd — 形容詞
- surdpositive
- surdercomparative
- surdestsuperlative
1. without sense, reason, or logical foundation; completely irrational in nature.
荒謬的
缺乏理性或不合邏輯的
without sense, reason, or logical foundation; completely irrational in nature.
The newspaper called the government's new tax policy surd and harmful to the economy.
該報稱政府的新稅制荒謬且有害經濟。
attributive use with 'and' coordination
Leo found his roommate's argument about the moon landing utterly surd.
Leo 覺得室友關於登月的論點完全不合邏輯。
Historians described the king's decision to raise taxes during a drought as surd.
史學家認為國王在乾旱期間加稅的決定毫無理性。
predicative: be + surd
Padma could not follow the surd reasoning in her opponent's speech.
Padma 完全無法理解對手演說中那些不合理的推論。
- surd argument
- surd decision
- surd reasoning
- surd policy
- utterly surd
- irrational
more common; overlaps in meaning but is widely used in both everyday and technical contexts
- unreasonable
everyday word for decisions or arguments that lack good sense
- absurd
stronger connotation of ridiculousness; more common than 'surd'
- reasonable
based on good sense and logic
- rational
showing clear and logical thinking
文法句型
surd + noun
be + surd
用法筆記
Very rare in modern English except in formal or literary writing. 'Irrational' and 'unreasonable' are much more common alternatives. The noun form 'surdity' exists but is also extremely rare.
常見錯誤
2. articulated with the vocal cords held apart so that air passes through without v
清音的
發音時聲帶不震動的
articulated with the vocal cords held apart so that air passes through without vibration; voiceless. Used to describe consonants in phonetics.
The 'k' in 'kite' is a surd consonant produced at the back of the mouth.
「kite」當中的「k」是在口腔後方發出的無聲子音。
attributive: surd + consonant
Benjamin practised saying surd and voiced pairs like 'f' and 'v' in front of the mirror.
Benjamin 對著鏡子練習發「f」和「v」這類無聲與有聲的配對音。
In the word 'stop', the first sound is surd, but the vowel that follows is voiced.
在「stop」這個字中，第一個音是無聲的，但後面的母音則是有聲的。
contrast surd vs voiced within one word
Layla noticed that all surd sounds in English can be made without using her voice at all.
Layla 發現英文裡所有的清音都可以完全不使用嗓音來發出。
- surd consonant
- surd sound
- surd stop
- surd fricative
文法句型
surd + noun
用法筆記
Almost entirely replaced by 'voiceless' in modern phonetics. You may encounter it in older linguistics textbooks or historical descriptions of sound systems.
同根字
- surdity名詞C2