The difference between Partner and Significant other

Partner as a noun:

Someone who is associated with another in a common activity or interest. A member of a business or law partnership. A spouse or other person with whom one shares a domestic, romantic or sexual bond. Someone with whom one dances in a two-person dance. Someone with whom one plays on the same side in a game, such as card games or doubles tennis.

Partner as a noun (nautical):

One of the pieces of wood comprising the framework which strengthens the deck of a wooden ship around the holes through which the mast and other fittings pass.

Partner as a noun (Jamaica):

A group financial arrangement in which each member contributes a set amount of money over a set period.

Partner as a verb:

To make or be a partner.

Partner as a verb:

To work or perform as a partner.

Significant other as a noun:

One's romantic partner, regardless of marital status or gender.

Significant other as a noun:

A person with whom one has an important bond of some kind.