Arbitrary vs Random: What’s the Difference? Meaning + Examples

People often use arbitrary vs random as if both words mean “any choice,” but they don’t. Random means a result is chosen by chance, like a coin flip, a lottery draw, or a shuffled list. Arbitrary means a person chose something without clear criteria, a rule, or a stated reason, which can sometimes feel unfair or inconsistent. This guide breaks down the difference in simple terms, shows arbitrarily vs randomly, and gives clear, copy-ready examples so you can pick the right word in school, work, and technical writing.

Quick Answer

Random means chosen by chance (like a lottery draw). Cambridge defines random as happening, done, or chosen by chance rather than according to a plan or pattern.
Arbitrary means chosen without a clear reason, rule, or system, and Oxford notes it can sometimes seem unfair.

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TL;DR

• Random = chance-based selection.
• Arbitrary = no stated reason/standard (often feels unfair).
• Something can be both (random method + people feel there’s “no reason”).
• In math/science, arbitrary is often neutral: any/unspecified.

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What does arbitrary mean?

Arbitrary usually means a decision or rule does not seem based on a reason, system, or plan, and it can sometimes seem unfair.
Cambridge also includes a sense where arbitrary can involve using unlimited personal power.

Plain-English meaning

Arbitrary = “picked without clear criteria.”
It often implies: “I don’t see the logic behind this choice.”

Common collocations: arbitrary decision, arbitrary rule, arbitrary deadline, arbitrary limit, arbitrary cutoff.

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What does random mean?

Random means happening, done, or chosen by chance, not according to a plan or pattern.
Merriam-Webster also frames random as lacking a definite plan/purpose/pattern, and includes examples like “random sample.”

Plain-English meaning

Random = “picked by chance.”
It implies a chance method (draw, shuffle, generator, lottery).

Common collocations: random sample, random selection, random check, chosen at random.

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Key Differences Between Arbitrary and Random

Arbitrary Meaning

Arbitrary means a choice made by personal judgment, whim, or convenience, without clear criteria or a consistent rule. It can sometimes imply bias, unfairness, or “no real reason.”

Example: Choosing a blue car just because you felt like it (not because of a requirement or rule).

Random Meaning

Random means something happens or is chosen by chance, without a plan or a deliberate reason—usually through a chance method like drawing, shuffling, or flipping a coin.

Example: Picking a winner by coin flip or drawing numbers from a hat.

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Arbitrary vs Random in Math and Statistics

Arbitrary in Math

In math, an arbitrary number usually means any value can be chosen. It’s not a “special” number—just a general one.

Example: “Let $x$x be an arbitrary number.”
Meaning: choose any number for $x$x.

Random in Statistics (Probability-Based)

In statistics, random usually implies a selection made using a probability process (a specific distribution or random method).

Example: “We took a random sample.”
Meaning: the sample was chosen using a chance-based procedure.

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Examples

Arbitrary Example

“The manager made an arbitrary decision to change the hours.”
Meaning: it was based on their own preference, not on a written policy or clear standard.

Random Example

“She made a random selection of names from the phone book.”
Meaning: the selection was done by chance, not by preference.

Use this simple test:

✅ Use random when…

A chance method decides it.

• Drawing names from a hat
• Using a random number generator
• Shuffling and picking blindly

✅ Use arbitrary when…

A person picks something without a stated reason, rule, or standard.

• “We picked Tuesday—no special reason.”
• “The rule changed and no criteria were explained.”

Memory trick:
Random = chance.
Arbitrary = no clear standard (often feels unfair).

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Quick comparison table

Word	Core idea	Best short example
Arbitrary	No clear reason/standard; can seem unfair	“An arbitrary deadline.”
Random	Determined by chance	“A random winner.”
Subjective	Based on personal opinion/taste	“Music taste is subjective.”
Strict	Rule-based and consistent	“A strict attendance policy.”

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How to choose the right word

1. Was there a chance process (draw/shuffle/generator)? → Random
2. Did someone choose it with no stated criteria? → Arbitrary
3. Was there a clear rule (alphabetical, rubric, policy)? → Often neither (it’s rule-based)

“Neither” examples

• Alphabetical groups (A–M / N–Z) = rule-based, not random
• First-come, first-served = rule-based, not random
• Rubric-based grading = rule-based, not arbitrary

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“Arbitrarily” vs “Randomly”

These are the adverbs:

Definition box

• Randomly = by chance, not according to a plan.
• Arbitrarily = without a clear reason/system; sometimes seems unfair.

Examples

• “They randomly selected 10 people for the survey.”
• “The leaders were chosen arbitrarily.”

Spelling note (SEO capture)

“Arbitarily” is a common misspelling. The correct word is arbitrarily.

Read More Related Article:

Arbitrary Meaning & Definition: Examples, Synonyms, and “Arbitrarily”

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15 examples you can copy

1. We picked a random winner by drawing a name from a hat.
2. The app chooses a random username if yours is taken.
3. They ran random checks at the entrance.
4. She opened the book to a random page.
5. The group used a generator to select randomly.
6. The new rule feels arbitrary because no criteria were shared.
7. They set an arbitrary limit of two pages with no explanation.
8. The deadline seems arbitrary and keeps changing.
9. He arbitrarily decided the meeting would start at 7 a.m.
10. The punishment looked arbitrary compared to similar cases.
11. The winner was chosen randomly, so the result feels “arbitrary” to people who wanted a reason.
12. Alphabetical grouping isn’t random; it’s rule-based (so it’s neither).
13. A coin flip is random, but choosing to flip a coin in the first place can be arbitrary.
14. In law/policy talk, people criticize arbitrary decisions that lack consistent standards.
15. In math, “pick an arbitrary value of $x$x” usually means “pick any value,” not “pick a random one.”

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Special contexts (where people get confused)

Arbitrary in math and science

In technical writing, arbitrary often means any/unspecified, not “by chance.”
Example: “Let $x$x be an arbitrary real number.” (= any real number)

Random in statistics

In statistics, random usually means a probability-based method (random sample, random assignment). Merriam-Webster explicitly references “a random sample.”

Arbitrary in law and policy (tone warning)

Oxford notes arbitrary can sometimes seem unfair, and Cambridge includes an “unlimited personal power” sense. So calling a workplace rule “arbitrary” can sound like an accusation.
Safer workplace wording: “unclear criteria,” “inconsistent,” “unevenly applied.”

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Professional email rewrites (copy/paste)

If you want a calm, non-accusatory tone:

• Instead of: “This is arbitrary.”
  Use: “Could you share the criteria behind this decision?”
• Instead of: “This feels random.”
  Use: “Can you explain how the selection was made?”
• Instead of: “You’re changing rules randomly.”
  Use: “It would help to have a consistent standard written down.”

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Arbitrary vs random synonym

Synonyms for random

• by chance, accidental, haphazard (context-dependent)

Synonyms for arbitrary

• capricious, whimsical, haphazard (tone-dependent)

Tip: “Haphazard” often implies messy/disorganized, not just chance.

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Common mistakes and quick fixes

• ❌ Mistake: Using random when a person just “picked something.”
  ✅ Fix: Use arbitrary if there was no stated reason or standard.
• ❌ Mistake: Using arbitrary when you mean strict.
  ✅ Fix: Strict can be consistent and rule-based; arbitrary suggests no clear basis.
• ❌ Mistake: Writing “That’s arbitrary” in an email (sounds accusatory).
  ✅ Fix: Say: “Could you share the criteria behind this decision?”

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Mini quiz

1. A lottery draw picks the winner. Is that arbitrary or random?
2. A manager changes the policy with no explanation. Is that arbitrary or random?
3. In math: “Let $x$x be an arbitrary number.” Does arbitrary mean random?

Answers:

1. Random
2. Arbitrary
3. No—here it means “any/unspecified.”

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FAQs

Is arbitrary the same as random?

No. Random is chosen by chance. Arbitrary is chosen without a clear reason or standard.

What’s the difference between arbitrarily and randomly?

Randomly means by chance. Arbitrarily means without a clear reason/system and can seem unfair.

Can something be both arbitrary and random?

Yes. A process can be random (chance-based), but people may still call it arbitrary if they wanted a reasoned standard instead of chance.

What word should I use in professional writing?

If you want a calm tone, use “unclear criteria” or “inconsistent” instead of “arbitrary,” unless you truly mean it.

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Conclusion

Arbitrary vs random comes down to one key idea: random is chosen by chance, while arbitrary is chosen without clear criteria, a rule, or a stated reason. If a process uses a draw, shuffle, or generator, random is the accurate word. If a person picks something “just because,” especially in rules, deadlines, or decisions, arbitrary fits and it can sound unfair or inconsistent. In professional writing, choose the precise word, and when tone matters, replace “arbitrary” with clearer, calmer phrasing like unclear criteria or inconsistent.