According to The British National Corpus the term “grass roots” is most frequently used in the UK quality press such as “The Guardian” and “The Independent”. The collocation is often found in articles about elections and political parties. It is also part of news scripts and interviews with politicians on central television.
To the right the most frequent nouns are level, organization(s) and tennis.
However, the term is also used in the popular press, too – “The Northern Echo”, “Liverpool Daily Post”. It can be found in the sports news sections for example.
The verbs most commonly used in collocations before the term “grass roots” are “serviced”, “is” and “cultivate”. The most common verb used after “grass roots” is “level”.
The Oxford Learner’s dictionary defines the term as “ordinary people in society or in an organization, rather than the leaders or people who make decisions”.
The Cambridge dictionary give the following meaning: “the ordinary people in a society or an organization, especially a political party”.
The Mariam-Webster dictionary has three meanings listed: 1. basic, fundamental; 2. being, originating, or operating in or at the grass roots; 3. not adapted from or added to an existing facility or operation - totally new.
The most frequently used meaning of the term “grass roots” is the one of The Cambridge dictionary.