How to spell ONCEIN correctly?

The correct spelling for "oncein" may depend on the intended meaning. If it is meant to be "once in", then the correct suggestion would be to add a space between "once" and "in". If it is meant to be a word on its own, more context is needed to make a correct suggestion.

• concern
• ocean The ocean is a vast body of saltwater covering almost three-quarters of the earth's surface.
• once I once saw a tiger in the zoo.

Ponnies

• panniers
• pennies
• peonies
• pones
• ponies