ad-lib lines

Translations
импровизировать реплики
During the play, he had to ad-lib lines due to a forgotten script.
Во время спектакля ему пришлось импровизировать реплики из-за забытого сценария.
Definitions
Ad-lib lines refer to spontaneous or improvised dialogue or remarks made by an actor, speaker, or performer, rather than scripted lines. This practice allows for a more natural and dynamic interaction, often enhancing the authenticity of a performance.