His off-script comments during the speech earned applause from the audience.

off-script 是由前缀 off-（表示"脱离"）和名词 script（"剧本、讲稿"）组成的复合形容词，字面意思是"脱离讲稿的"，引申为"即兴发挥的、不按稿子说的"。