Meaning and Usage
"てっきり" is an adverb used to express a strong assumption or belief that something is true or certain, often followed by a surprising or contrary fact. It conveys the speaker's confidence in their assumption, which turns out to be mistaken.
Common Contexts
It is frequently used in everyday conversation when someone is surprised that their expectation was wrong. The tone is usually casual to neutral, and it often appears with verbs like 思う (to think) or believed contexts.
Typical Collocations
- てっきり～と思う: "I was sure that..."
- てっきり～だと思っていた: "I had been certain that..."
These patterns emphasize the speaker's mistaken certainty.
Register and Nuance
"てっきり" is informal to neutral and common in spoken Japanese. It is not typically used in formal writing.
Common Learner Mistake
Learners sometimes confuse "てっきり" with words that simply mean "definitely" or "certainly" without the nuance of mistaken assumption. Remember, "てっきり" implies the speaker was sure but turned out to be wrong.