odd number
Intermediate (B1)Neutral, with a strong technical register in mathematics.
Definition
Meaning
An integer that is not divisible by two without leaving a remainder.
Beyond mathematics, sometimes used metaphorically to describe things that are unusual, irregular, or not matching a set.
Linguistics
Semantic Notes
A compound noun formed from the adjective 'odd' and the noun 'number'. Its mathematical definition is precise, but its metaphorical use is vague.
Dialectal Variation
British vs American Usage
Differences
No significant differences in mathematical meaning. 'Odd' used alone (e.g., 'odd socks') is more common in UK English than US for describing mismatched items.
Connotations
Neutral in mathematical context. Can carry connotations of strangeness or irregularity in metaphorical use.
Frequency
Equally frequent in educational and technical contexts in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
be an odd numberadd/choose/select an odd numberan odd number of (objects/people)end in an odd numberVocabulary
Synonyms
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “odd man out (related concept)”
Usage
Context Usage
Business
Rare, except in data analysis or scheduling (e.g., 'an odd number of board members to avoid ties').
Academic
Common in mathematics, statistics, and computer science textbooks and lectures.
Everyday
Used in basic arithmetic, games, and simple grouping tasks (e.g., 'We need an odd number of teams for the tournament').
Technical
Precise definition in arithmetic; fundamental concept in number theory.
Examples
By Part of Speech
verb
British English
- This function odd-numbers the list, removing all evens.
- The system automatically odd-numbers the pages in that section.
American English
- The software odd-numbers the entries for the audit trail.
- Please odd-number the items on this inventory sheet.
adjective
British English
- The odd-numbered houses are on the left side of the street.
- Check the odd-numbered questions for homework.
American English
- The odd-numbered pages have the appendix information.
- She parked in an odd-numbered spot.
Examples
By CEFR Level
- Three, five, and seven are odd numbers.
- Our house has an odd number.
- You need an odd number of players for this game.
- The total came to an odd number, which seemed suspicious.
- The algorithm filters out data points associated with odd numbers in the sequence.
- To break a tie vote, the committee should have an odd number of members.
- The cryptographic protocol relies on the properties of large prime odd numbers.
- He noted the odd-numbered chapters were purely theoretical, while the evens contained practical applications.
Learning
Memory Aids
Mnemonic
Think of a single sock left over when pairing them - it's the 'odd' one out, just like an odd number is left over when you try to divide it into two equal groups.
Conceptual Metaphor
NOT BEING PAIRED / NOT MATCHING (from the idea of pairing numbers into twos).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid translating 'odd' as 'странный' in this mathematical context; the correct term is 'нечетное число'.
- Note the fixed word order: 'odd number', not 'number odd'.
Common Mistakes
- Using 'odd' to mean 'approximately' (e.g., 'odd 20 people' is incorrect).
- Confusing 'an odd number of people' (e.g., 5 people) with 'a few odd people' (e.g., strange people).
Practice
Quiz
In which sentence is 'odd number' used metaphorically?
FAQ
Frequently Asked Questions
No, zero is an even number because it is divisible by 2 without a remainder.
No, the term strictly applies to integers. Numbers like 3.5 or 1/3 are not classified as odd or even.
The opposite is an 'even number', which is any integer divisible by 2.
It is a fundamental classification in arithmetic and number theory, crucial for understanding divisibility, patterns, and many algorithms in mathematics and computer science.