There area at least two other terms which enter the history of the Symbol ‘0’. The term: Śūnyathā [‘Emptiness’]. And the term Nāmarūpa.
Nāmarūpa, in English: ‘Form’, is a term that originated in the Platonic Dialogues and was then appropriated into Logic’s emerging new vocabulary. I have devoted a whole Post to its meaning in the section on Logic. So take a look.
Both terms enter the stage in the Hridaya Sūtra [‘Heart Sūtra’], the 25 Sloka compacting of the MahaPrajñāpāramithā, although the latter has a longer history.
The term Śūnyathā has its roots in the problematic extension of an earlier term ‘That-ness’ which is commonly interpreted in scholarly circles as an abstraction of ‘That’.
You can’t abstract ‘That’. It has gone well-beyond such binary divides as concrete and abstract. If you don’t see that, you haven’t understood ‘That’. [See the Post]. The same applies to Śūnyathā when it is, as is common, treated as an abstraction of Śūnyam.
At last count I know of at least 6 different definitions of Śūnyathā, from the early Theravada Schools to the later Mahayana appropriations. So watch out.
The only stable definition that has stood steady over time is as Śūnyathāsūnyathā: the Emptiness of Emptiness itself.
A Self-Eating Expression. Naturally. Necessarily.