This means that the keyword is probably a "transactional" keyword. There are other names for such keywords such as "conversion" keywords (see the purchase/conversion funnel below).
Transactional keywords: those that are linked to a user who is about to make a transaction or conversion.
Navigational keywords: those used to find a specific brand or site.
Informative keywords: those related to general information on a topic.
Cost per click
Cost per click, while clearly a PPC metric, can also to some extent inform the relative importance of organic keywords. If you assume that people bidding on keywords are presumably rational people, then generally the higher the average bid for a term, the more likely it is to lead to a conversion. Or it may have some other value to the bidding company, such as brand awareness or demand generation. It's a signal you can use to understand the relative "value" of the keyword.
Conversion potential
Just like cost-per-click data, the more likely a term is to lead to a conversion, the higher the priority. If you have enough data, you can pull PPC conversion data from Google Analytics and combine it with your other keyword data (using a pivot table). Terms that include “price,” “for sale,” etc., indicate that it is more likely to be a term that is close to converting and therefore of higher importance.
Relevance
Relevance is going to be a bit of a judgement call. Having a deep understanding of the company or website, its users, its goals, etc., should give you an idea if a term is relevant to the products or services offered by the site.
Position in keyword research or sales funnel
In addition to the overall “importance” of a keyword, you should be able to filter keywords and determine where they are in the conversion or sales funnel . This information will be useful when communicating with departments and stakeholders, as well as help determine the strategy for ranking for those keywords.