not (really) infectious

Not really!

The word really is there just for added emphasis, but is not an essential. English, particularly American dialect, is full of non-essential, descriptive words (usually adverbs and adjectives) for emphasis.

Thanks. Ragman.

I'm not sure that's a complete picture--"not really infectious" can also mean it's a bit infectious, but not very--your chances of getting infected might be 1 in 100, say, instead of maybe 1 in 2, if it were very infectious. It can also be a kind of intensifier (or in this case kind of a negative intensifier. I guess that would make it a deintensifier.) Whereas "not infectious" means that I can't get it from the "you" that has it.

'... not really infectious' seems to be quite confusing. Ragman has a different view from Monerey Jack, and I wonder what the correct interpretation is.

They're BOTH correct. That's the thing. It's usually not either/or. The theoretical linguists will tell you that language is inherently ambiguous and that in general you can't make it totally non-ambiguous. And as we keep telling you, there are usually multiple distinctly different ways to say the same thing.

That would be my reading of the difference between the two sentences, too.

ie "Not infectious" is an absolute, while "not really infectious" means that you CAN infect others, but it is not very likely that you will.

yay deb.

I agree that another possible interpretation could occur. Well done to those that brought that up. This is, at best, an ambiguous phrase.

Okay my two cents worth:

The first sentence says with confidence that you cannot transmit your cold to others. Addition of 'really' where it is placed in the sentence implies that you cannot transmit your cold to others in the technical sense, but that other (presumed) negatives involving others likely exist.

However if you say it like this: "Really, your type of cold is not infectious" you are emphasizing the first sentence as fact.

I've been speaking the sentence aloud to myself, and I think you'd say them slightly differently if these were spoken rather than written. If you were using the "really" as an intensifier to emphasize you couldn't get it, I'd stress "really" more and there would be a slight pause before "infectious", but if I were saying that it's a little infectious but not very, very infectious, I think both words would have equal stress and be said together, no pauses. But someone would have to be listening really closely to hear the difference. Problem is, when they're written there's no way to indicate different stress.