in idea

Adverb

not-comparable

In thought or imagination as opposed to in reality; as an abstract concept; conceptually.

Japanese Meaning

実際の事象や事物ではなく、思考や想像の中での概念として存在するさま / 抽象的な概念として扱われる状態 / 概念上、理論的な意味合いを持つこと

She was, in idea, the leader of the movement even though she held no official title.

彼女は正式な肩書きはなかったが、心の中ではその運動の指導者だった。

Sense（1）

In thought or imagination as opposed to in reality; as an abstract concept; conceptually.