extemporaneously

Adverb

not-comparable

In an extemporaneous manner; without prior preparation or planning.

Japanese Meaning

事前の準備や計画なしに行われる様子、即興で行われること

She spoke extemporaneously at the conference when the projector failed, and her improvised remarks impressed the audience.

プロジェクターが故障したとき、彼女は会議で即興で話し、その場で作った発言が聴衆を感心させた。

Sense（1）

In an extemporaneous manner; without prior preparation or planning.

Considering that he was speaking extemporaneously, he covered the subject pretty well.