The original full Japanese name behind the international Pokémon brand is Pocket Monsters.
The Japanese title is ポケットモンスター, romanized as Poketto Monsutā. It was commonly shortened to Pokémon, a contraction that became the franchise’s international name. The acute accent over the e was added in overseas branding to guide pronunciation.
The name refers both to the fictional creatures and to the wider franchise of games, animation, films, cards and merchandise. In Japan, the first video games were released under the Pocket Monsters name, while international releases used Pokémon Red and Blue rather than Red and Green.
The word Pokémon is also grammatically unusual in English because its singular and plural forms are identical: one Pokémon and many Pokémon. “Pocket Monsters” is therefore the original brand name, not the name of a separate series or creature category.