Definitions

1. noun

A person who travels in space, especially in the cosmos, particularly the ocean of space or the cosmos, or a person trained to live and work in space.

“The oceanaut spent several months on the space station studying the effects of zero gravity on the human body.”

2. noun

A person who travels to the ocean, especially for scientific research or exploration.

“The team of oceanauts embarked on an expedition to study the marine life in the deep ocean.”