The grass roots of an organization or movement are the ordinary people who form the main part of it, rather than its leaders.
You have to join the party at grass-roots level.
grass roots in British English
plural noun
1.
a.
the ordinary people as distinct from the active leadership of a party or organization: used esp of the rank-and-file members of a political party, or of the voters themselves
b.
(as modifier)
the newly elected MP expressed a wish for greater contact with people at grass-rootslevel
2.
the origin or essentials
Word origin
C20: sense 1 originally US, with reference to rural areas in contrast to the towns
grass-roots in British English
(ˈɡrɑːsˌruːts)
adjective
1.
relating to the ordinary people as distinct from the active leadership of a partyor organization: used esp of the rank-and-file members of a political party, or ofthe voters themselves
grass-roots support for the new party
She joined the party at grass-roots level.
a grass-roots candidate
2.
relating to the origin or essentials
Changes to the game have been made at grass-roots level.
grass roots in American English
1. US
the common people, orig. those esp. of rural or nonurban areas, thought of as best representing the basic, direct political interests of the electorate
2. US
the basic or fundamental source or support, as of a movement
Derived forms
grass-roots (ˈgrass-ˈroots) (ˈgræsˈruts)
adjective
In other languages
grass roots
British English: grass roots NOUN
The grass roots of an organization or movement are the ordinary people who form the main part of it, rather than its leaders.