# residue

/ˈɹɛzəˌdu/ (US) · /ɹˈɛsɪdjˌuː/ (UK)

Source: https://englishreference.com/word/residue
Updated: 2026-06-20

## Senses

### 1. leftover substance

noun · CEFR C1 · Technical

a small amount of something that stays on a surface after the rest has been removed.

For teachers: the material or substance that remains after a process such as evaporation, combustion, or filtration.

- The sticker left a sticky residue on the window that was hard to clean.
- The laboratory analysis detected a chemical residue on the surface of the fruit, suggesting that pesticides had been applied shortly before harvest.

Usage: Often used as an uncountable noun when referring to a layer of material.

### 2. legal remainder

noun · CEFR C1 · Formal · Technical

the part of a person's money or property that is left after all debts and specific gifts are paid.

For teachers: the portion of a testator's estate remaining after the payment of debts, funeral expenses, and specific legacies.

- After the house was sold and the bills were paid, the residue of the money went to charity.
- The will stipulated that the residue of the estate should be divided equally among the deceased's three grandchildren after all specific bequests were fulfilled.

Usage: Typically used in the context of wills and probate law.

### 3. math remainder

noun · CEFR C2 · Technical

the number that is left over after one number is divided by another.

For teachers: a representative element of an equivalence class; the remainder left after a division operation in modular arithmetic.

- In this calculation, we need to find the residue of seventeen modulo five.
- The student struggled to calculate the quadratic residue, a fundamental concept in advanced number theory and cryptography.

### 4. biochemistry unit

noun · CEFR C2 · Technical

a single part of a larger molecule, like one link in a chain.

For teachers: a specific unit within a polymer, such as a single amino acid within a protein chain.

- The protein is made of a long string of amino acid residues.
- The researchers identified a specific cysteine residue that was essential for the enzyme's catalytic activity.

## Examples

- The sticker left a sticky residue on the window.
- After the water evaporated from the pan, a thin white residue of salt remained on the bottom.
- The laboratory analysis confirmed that a toxic residue had permeated the soil, suggesting that the industrial waste had not been neutralized as previously claimed.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.