adverb[usually as submodifier]
Deceptively belongs to a very small set of words whose meaning is genuinely ambiguous in that it can be used in similar contexts to mean both one thing and also its complete opposite. A deceptively smooth surface is one that appears smooth but in fact is not smooth at all, while a deceptively spacious room is one that does not look spacious but is in fact more spacious than it appears. But what is a deceptively steep gradient? Or a person who is described as deceptively strong? To avoid confusion, use with caution (or not at all), unless the context makes clear in what way the thing modified is not what it first appears to be.