delta

/ˈdeltə/ (bre, ipa) · [dˈɛltə] /ˈdeltə/ (ame, ipa) · [dˈɛltə] /ˈdel-tə/ (ame, mw)

delta — 名詞

  • deltasingular
  • deltasplural

1. a wide, fan-shaped tract of land at a river's mouth, formed as the main stream s

1.名詞B1
釋義

三角洲；河口

河流入海口處的沖積平原

a wide, fan-shaped tract of land at a river's mouth, formed as the main stream splits into separate channels that empty into the ocean or a large lake.

例句

The Nile Delta is known for its rich soil and large farming communities.

尼羅河三角洲以其肥沃的土壤和大型農業社區而聞名。

proper noun: the Nile Delta as a named region

Ishaan studied the map and saw the river formed a wide delta at the coast.

Ishaan 看著地圖，看見河流在海岸處形成了一個寬廣的三角洲。

同義詞
  • estuary

    an estuary is where a river meets the sea with a single, wide channel affected by tides; a delta has multiple branching channels.

  • floodplain

    a flat area beside a river that floods; a delta is specifically at the river mouth where it splits.

用法筆記

Often capitalised as part of a place name, e.g. the Nile Delta, the Mekong Delta.

常見錯誤

❌The river creates a delta of the mountain.
✅Rivers form deltas where they meet the ocean or a lake.
💡a delta is formed at a river's mouth, not at its source or along a mountain range.

2. Delta (Δ, δ) is the character that occupies the fourth position in the Greek wri

2.名詞B1
釋義

希臘字母

第四個希臘字母（Δ/δ）

Delta (Δ, δ) is the character that occupies the fourth position in the Greek writing system, and is widely used as a symbol in mathematics and science.

例句

In maths class, the teacher used delta to show a change in a number.

在數學課上，老師用希臘字母 delta 來表示數值的變化。

usage in mathematics to represent change

Nadia wrote a small delta symbol next to the equation.

Nadia 在方程式旁邊寫了一個小寫的 delta 符號。

用法筆記

In science and mathematics, the uppercase Δ is commonly used as a symbol meaning 'change in' (e.g. Δt = change in time). The lowercase δ often means a small amount.

常見錯誤

❌Delta is the third letter of the Greek alphabet.
✅Delta is the fourth letter of the Greek alphabet.
💡delta comes after gamma, not before it.

3. a fast-spreading strain of the coronavirus that causes COVID-19, given the name

3.名詞B2
釋義

Delta株

COVID-19 的高度傳染性病毒株

a fast-spreading strain of the coronavirus that causes COVID-19, given the name Delta by global health authorities in 2021, which quickly became the most common source of new infections around the world.

例句

Many countries closed their borders again when the Delta variant began to spread quickly.

Delta 變異株開始迅速傳播時，許多國家再次關閉了邊境。

historical context: travel restrictions during Delta wave

Hao got vaccinated at the end of 2021 to protect himself against the Delta variant.

Hao 在 2021 年底接種了疫苗，以保護自己免受 Delta 變異株的感染。

同義詞
  • variant

    a general term for any mutated form of a virus; 'Delta' is a specific named variant.

  • strain

    similar to variant, but often used more broadly for any distinct subtype of a microorganism.

用法筆記

Usually capitalised (Delta variant) as a proper name assigned by the WHO naming system for variants of concern. Now mostly of historical reference since the Omicron variant replaced it.

常見錯誤

❌The Delta variant refers to a river landform.
✅The Delta variant was a contagious form of the COVID-19 virus.
💡in health news, 'Delta' refers to the virus variant, not the geographical feature.

4. any object or shape that looks like a triangle, named after the triangular form

4.名詞B2
釋義

三角；Δ形

形似希臘字母 Δ 的形狀

any object or shape that looks like a triangle, named after the triangular form of the capital Greek letter delta (Δ).

例句

The Concorde aircraft had a distinctive delta wing that swept back in a wide triangle.

協和客機的三角翼以大三角形的形狀向後掠展，成為它的顯著特徵。

compound: delta wing for a triangular aircraft wing shape

Talia pointed at the delta-shaped road sign that warned drivers about the sharp bend ahead.

Talia 指著那個 Δ 形狀的交通標誌，提醒駕駛人前方有急彎。

collocation: delta-shaped road sign

同義詞
  • triangle

    triangle is the general geometric term; delta is used when the shape specifically resembles the Greek letter Δ.