Cool MateCompletely vs Flat out
When to use each in English, with meaning, register, and examples.
Completely
Top 1,000 (very common)A2adverb
Flat out
InformalTop 2,000 (common)
Most formal: CompletelyMost common: Completely
| Completely | Flat out | |
|---|---|---|
| Pronunciation | 🇬🇧 /["/kəmˈpliːtli/"]/🇺🇸 /["/kəmˈpliːtli/"]/ | 🇬🇧 //flæt aʊt//🇺🇸 //flæt aʊt// |
| Meaning | Totally or fully. | Completely and without stopping |
| Example | I completely forgot about the meeting today. | I am working flat out to finish this project on time. |
| Register | Neutral | Informal |
| How common | Top 1,000 (very common) | Top 2,000 (common) |
| CEFR level | A2 | - |
| Part of speech | adverb | |
| Collocations | completely agree, completely understand, completely satisfied, completely different, completely unaware | run flat out, work flat out, drive flat out, be flat out busy, go flat out |
| Antonyms | partially, incompletely, somewhat | - |
| Common mistakes | Using 'completely' without a verb or action., Confusing 'completely' with 'totally' in formal contexts., Saying 'completely' in casual situations where simpler words like 'really' might fit better. | Using 'flat out' in overly formal contexts., 'Flat out' confused with its literal meaning, thinking it's only about physical flatness., Misusing it for less intense situations. |
| Usage notes | Use 'completely' to emphasize the totality of an action or state. It's suitable for both spoken and written English but might sound overemphasized in casual conversation. | Used informally to describe doing something to the fullest or without exception. Avoid in formal writing. |
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Frequently asked questions: Completely vs Flat out
What's the difference between Completely and Flat out?
Completely: Totally or fully. Flat out: Completely and without stopping
Which is more formal: Completely and Flat out?
Completely is the most formal of these.
Which is more common: Completely and Flat out?
Completely is the most common in everyday English.
Can you show an example of each?
Completely: I completely forgot about the meeting today. Flat out: I am working flat out to finish this project on time.
Can I use Completely and Flat out interchangeably?
Not always. Completely and Flat out 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.