say it: GRAS-roots
grassroots is an adjective meaning "fundamental". It carries 2 recorded senses.
of or involving the common people as constituting a fundamental political and economic group
“a grassroots movement for nuclear disarmament”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for grassroots come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.