YouGov conducted a similar poll about no-deal (and other Brexit-related terms) in January of 2019. Rather than asking people what it means, it asked how familiar they were with a set of Brexit outcomes. The results are summarised in the figure below.
If we compare it to the other options, we see 'no-deal' is the option more people are familiar with (going by the bright purple only, or the bright and faded purple combined) than any of the other options.
According to this poll, 74% of people know what 'no-deal' means, at least to some extent. It doesn't exactly correspond to the result in the question, but it's not super different either.
The full results of this poll can be found here.