noun / verb
partner
PART-nur/ˈpɑːrtnər/
A person or organization joined with another in a shared undertaking.
Each business partner signs the shared plan at the shop.

Etymology
Parçonier meant a joint owner or heir, making shared possession the central image. The word may also reflect an expression meaning 'part holder,' likewise connecting association with a shared portion.
In context
partner you also might depend on your partner for emotional Comfort
More examples
- She and her partner are raising two children.
- The library partners with local schools to offer tutoring.
- Choose a partner for the next exercise.
Forms
partner · partners · partnered · partnering
partnership noun — A relationship involving shared work or responsibility.
Similar words
- associate
- Suggests a professional connection without necessarily sharing ownership or responsibility.
- collaborator
- Emphasizes working together on a particular project or task.