noun
A somewhat literary or formal word for a playful or witty remark; less common in casual speech than 冗談.
彼の言葉は単なる戯言に過ぎない。
His words are nothing more than a joke.
冗談 is the common, everyday word for 'joke'; 戯言 is more literary and less frequently used.
The exact derivation is uncertain; the kanji 戯 (play, frolic) and 言 (word) combine to suggest playful speech.