In the UK, "aubergine". I think this is a well-established UK/US variation. I don't know what is common in other English-speaking countries.

We say "eggplant" in Australia, and we use "aubergine" to mean the colour of eggplant.

Eggplant

'Aubergine' is used in the UK and Ireland. 'Eggplant' is used in the US, and also Australia/NZ, I believe. British cuisine has always been strongly influenced by French in the terms it uses. For example, British English uses the French term 'courgette', while the US, influenced by its Italian immigrants, uses 'zucchini'. British English uses 'coriander', taken from the French 'coriandre', while Americans say 'cilantro' because of the heavy Hispanic influence in the US.