What's the definition of the idea of "play" as developed by Jacques Derrida?

Derrida's 1966 lecture "Structure, Sign and Play in the Discourse of the Human Sciences"  at the conference in Johns Hopkins University is generally accepted by critics to mark the beginning of Post-Structuralism. Derrida expressed his reservations and remarked on the limitations of structuralism.

Derrida's main argument was that the structuralists were trying to seek unity in all  aspects of human activities by glossing over inherent contradictions and ambiguities and imposing a false sense of complacency.

Derrida on the other hand reacted by emphasizing these inherent contradictions, inconsistencies and ambiguities. 'Play' refers to the impossibility of seeking a single unified meaning in any given context, thus resulting in an acceptance of the ambiguities and inconsistencies of human existence.