nonfrivolous

adjective
non·​friv·​o·​lous | \ ˌnän-ˈfri-və-ləs How to pronounce nonfrivolous (audio) \

Definition of nonfrivolous

: not lacking importance, seriousness, or a sound basis : not frivolous a nonfrivolous lawsuit

First Known Use of nonfrivolous

1892, in the meaning defined above

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