What was the Pokémon project originally called before Pocket Monsters?

The Pokémon project was originally called Capsule Monsters.

Satoshi Tajiri initially used the name Capsule Monsters for his creature-collecting game concept. The name reflected the idea of monsters being stored in capsules, but the term could not be trademarked, so the project was renamed Pocket Monsters.

“Pocket Monsters” became the Japanese title of the first games, Pocket Monsters Red and Green. The abbreviated form Pokémon was used internationally, with an acute accent added to the e to help indicate the intended pronunciation.

The name change is sometimes simplified as though Pokémon began with the English abbreviation. In fact, the franchise's original Japanese title came first, and the familiar international name developed from that title. The naming history also explains why “Pocket Monsters” remains part of the franchise's Japanese identity.