A spouse is a person's husband or wife. When two people get married, they become spouses to each other. Your parents are spouses if they're married, and your teacher might mention her spouse when talking about her husband or wife.

The word works equally well for either partner in a marriage. Instead of having to say “her husband or his wife,” you can simply say “their spouse.” This makes it especially useful in formal writing or when you don't know which person in a marriage you're talking about.

You'll often see spouse in official contexts: forms at the doctor's office ask you to list your spouse, insurance companies want to know about spouses, and legal documents refer to spouses rather than using the more casual words “husband” or “wife.” While those everyday words work perfectly fine in conversation, spouse sounds more professional and works in any situation.

The plural is spouses. When a company invites employees and their spouses to a dinner, they mean everyone should bring their spouse.