Enquiry vs Inquiry vs Investigation vs Question vs Request

When to use each in English, with meaning, register, and examples.

Enquiry

Top 5,000 (fairly common)B2noun

Inquiry

Top 3,000 (common)B2noun

Investigation

Top 2,000 (common)B2noun

Question

Top 1,000 (very common)A1noun

Request

Top 1,000 (very common)A2noun
 EnquiryInquiryInvestigationQuestionRequest
Pronunciation🇬🇧 /["/ɪnˈkwaɪəri/"]/🇺🇸 /["/ˈɪnkwəri//ɪnˈkwaɪəri/"]/🇬🇧 /["/ɪnˈkwaɪəri/"]/🇺🇸 /["/ˈɪnkwəri//ɪnˈkwaɪəri/"]/🇬🇧 /["/ɪnˌvestɪˈɡeɪʃn/"]/🇺🇸 /["/ɪnˌvestɪˈɡeɪʃn/"]/🇬🇧 /["/ˈkwestʃən/"]/🇺🇸 /["/ˈkwestʃən/"]/🇬🇧 /["/rɪˈkwest/"]/🇺🇸 /["/rɪˈkwest/"]/
MeaningA question or a request for information.A question or asking about something.Looking into something to find out more about it.A sentence or phrase that asks for information.to ask for something
ExampleI made an enquiry about the availability of the product.The teacher encouraged an inquiry into the reasons behind climate change.The police launched an investigation into the missing person's case.The teacher asked a difficult question during the exam.I would like to make a request for a day off next week.
RegisterNeutralNeutralNeutralNeutralNeutral
How commonTop 5,000 (fairly common)Top 3,000 (common)Top 2,000 (common)Top 1,000 (very common)Top 1,000 (very common)
CEFR levelB2B2B2A1A2
Part of speechnounnounnounnounnoun
Collocationsdetailed, thorough, full, carry out, conduct, have, be underway, take place, begin, report, team, process, at an/​the enquiry, during an/​the enquiry, in an/​the enquiry, a steward’s enquiry, the outcome of an enquiry, the result of an enquiry, exhaustive, extensive, thorough, flood, stream, make, pursue, send, desk, office, service, pending enquiry, enquiry about, enquiry as to, direct an enquiry to somebody, careful, systematic, further, encourage, enquiry concerning, enquiry into, an area of enquiry, a board of enquiry, a commission of enquirymake an inquiry, conduct an inquiry, primary inquiry, formal inquiry, inquiry processcareful, close, detailed, carry out, conduct, pursue, demonstrate something, reveal something, show something, on investigation, under investigation, investigation into, the subject of an investigation, careful, close, detailed, carry out, conduct, pursue, demonstrate something, reveal something, show something, on investigation, under investigation, investigation into, the subject of an investigationawkward, difficult, embarrassing, ask (somebody), have, address, question about, question as to, question concerning to, awkward, difficult, embarrassing, ask (somebody), have, address, question about, question as to, question concerning to, burning, challenging, controversial, bring up, pose, raise, arise, go unanswered, remain unanswered, question about, question for, question of, come into, call into, be open to, beyond question, in question, without questionspecial, legitimate, reasonable, make, put in, send, at somebody’s request, by request, on request, available on request, available upon request, by popular request, special, legitimate, reasonable, make, put in, send, at somebody’s request, by request, on request, available on request, available upon request, by popular request
Antonymsanswer, responseanswer, responsedisregard, neglect, overlookanswer, solutionrefuse, decline
Common mistakesConfused with 'inquiry'; 'enquiry' is often British English., Using 'enquiry' in informal contexts where 'question' is more suitable., Incorrect pluralization; 'enquiries' should not be replaced with 'enquiries'.Used incorrectly as 'inquiries' instead of 'inquiry' when talking about one question., Confused with 'enquiry'; remember 'inquiry' is more formal., Not using 'make' to form the phrase 'make an inquiry'.Confused with 'invest' which means to put money into something., Using 'investigation' as a verb instead of a noun., Mixing up 'investigation' with 'inspector', which refers to a person.Confusing 'question' with 'query' in formal contexts., Using 'questions' as a singular noun, e.g., 'I have a question' instead of 'I have questions.'Using 'request' with a different preposition, such as 'request for'., Confusing 'request' with 'require'., Not using it in the correct form, like 'requested' instead of 'requesting'.
Usage notesUse 'enquiry' in formal or business contexts when asking for information. In casual conversations, 'question' may be more common. Avoid using 'enquiry' in very informal settings.Use 'inquiry' in formal situations like business or academic contexts, not in casual conversations. It’s suitable for asking for information or clarification.Use 'investigation' in formal contexts, like police work or research. Avoid in casual conversations.Use 'question' in both formal and informal settings. It's appropriate in classrooms, interviews, and casual conversations. Avoid using in situations where a statement is expected.Used in polite or formal contexts. It may sound too formal for casual conversations, where simpler words like 'ask' are preferred.

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Investigation

Frequently asked questions: Enquiry vs Inquiry vs Investigation vs Question vs Request

What's the difference between Enquiry, Inquiry, Investigation, Question, and Request?

Enquiry: A question or a request for information. Inquiry: A question or asking about something. Investigation: Looking into something to find out more about it. Question: A sentence or phrase that asks for information. Request: to ask for something

Are Enquiry, Inquiry, Investigation, Question, and Request the same CEFR level?

Enquiry: B2, Inquiry: B2, Investigation: B2, Question: A1, Request: A2 on the CEFR scale.

What part of speech are Enquiry, Inquiry, Investigation, Question, and Request?

Enquiry: noun, Inquiry: noun, Investigation: noun, Question: noun, Request: noun.

Can you show an example of each?

Enquiry: I made an enquiry about the availability of the product. Inquiry: The teacher encouraged an inquiry into the reasons behind climate change. Investigation: The police launched an investigation into the missing person's case. Question: The teacher asked a difficult question during the exam. Request: I would like to make a request for a day off next week.

Can I use Enquiry, Inquiry, Investigation, Question, and Request interchangeably?

Not always. Enquiry, Inquiry, Investigation, Question, and Request are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.

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