Based on the text, the word you’re looking for is mudra.
Here’s how the text describes its origin and evolution:
* it began as an imprint used in writing.
* This imprint became the Sanskrit word for the stamp or seal used by Indian kings to authenticate decrees.
* It then evolved to signify a spiritual seal representing a yogi’s internal state.
* Later, it became a specific gesture used in yoga, alongside asana and mantra, to facilitate inner attitudes.