unseriously in English dictionary unseriously Meanings and definitions of "unseriously" In an unserious way; flippantly, frivolously. adverb In an unserious way; flippantly, frivolously. more Grammar and declension of unseriously unseriously ( comparative more unseriously, superlative most unseriously) unseriously (comparative more unseriously, superlative most unseriously) more Sample sentences with "unseriously" Declension Stem Try again Authors