I've heard people saying "I'm not too sure" on the internet. I guess it means the same as "I'm not very sure".
Is such a usage of the word "too" actually colloquial or could you also use it in a formal text?
I've heard people saying "I'm not too sure" on the internet. I guess it means the same as "I'm not very sure".
Is such a usage of the word "too" actually colloquial or could you also use it in a formal text?
If your question is about 'too,' not the phrase 'too sure,' then yes, too can be used in a formal text. This is from Grammerly.com
How to Use Too
Too is also a useful little word, but it’s not a preposition like to, and it doesn’t have as many meanings. You can use it instead of “besides,” “in addition,” “also,” or “as well.” But you can use it for other things, too, like when you want to indicate excessiveness. If you find grammar tough, you can say that it’s too hard. In casual speech, speakers sometimes use too in the sense of “very”: That gal is too funny!
It's probably that final sense that you're worried about; 'very' is a degree adverb, used before adjectives, verbs or other adverbs to show intensity. 'Too' denotes excessiveness.
"She was very angry," tells us she was more than a little angry. If you said, "She was too angry," it implies she was angrier than the situation demanded, or unreasonably angry.
When using too in an ironic sense (that is, to mean the opposite), as in "Too cute!" or "Too funny!," what you're really implying is that whatever you're talking about is very cute or very funny, as in 'too marvelous for words;' so marvelous you can't describe it.
Because of this seemingly contradictory meaning, you should be careful not to use 'too' unless you really mean excessive, and not as an intensifier.