Is teammate one word? Yes. In modern English, teammate is a closed compound noun written as a single word without a space or hyphen. If you write team mate with a space, you're using an outdated spelling that major dictionaries and style guides dropped decades ago.
Understanding how this compound word functions helps you maintain a polished, professional tone across emails, project documents, and company handbooks. Let's look at why this spelling is standard, how other similar terms work, and where writers often slip up.
The Short Answer and Dictionary Consensus
If you check major lexical authorities, the single-word spelling is the undisputed standard. Merriam-Webster lists teammate as a single entry with no spaces. The Oxford English Dictionary confirms that the closed compound form became the dominant spelling in American and British English during the latter half of the twentieth century.
When nouns merge in English, they typically go through three distinct phases:
- Two separate words (team mate)
- A hyphenated compound (team-mate)
- A closed, single word (teammate)
Teammate has fully completed this progression. Writing it as two words looks like a typo to modern readers and signals a lack of attention to detail in professional correspondence.
Why Compound Nouns Close Over Time
English is efficient. When two nouns or a modifier and a noun appear together frequently, writers naturally merge them to speed up reading comprehension. Think of how database, workflow, feedback, and backlog evolved. They started as separate concepts or hyphenated phrases before fusing into single words.
Language evolution favors reduced friction. When your brain processes teammate, it recognizes a single lexical unit representing a person you work alongside. Adding a space forces the brain to process two distinct concepts—a team and a mate—which can momentarily confuse the reader or evoke nautical terminology rather than office collaboration.
Comparing Similar Workplace Compound Words
The rules governing teammate apply to many other common collaboration terms. Getting these right keeps your copy consistent:
- Workplace: One word. Never work place.
- Coworker: One word (though some style guides still accept the hyphenated co-worker). Never co worker.
- Feedback: One word. Never feed back (unless you're using it as a verb phrase: "Please feed back the results to the team").
- Cross-functional: Hyphenated because it's a compound modifier preceding a noun.
Notice the distinction with verbs versus nouns. You feed back information to a colleague, but you collect feedback. You work alongside a teammate, but you don't team mate them. Keeping these parts of speech straight prevents common grammatical errors in business writing.
Common Mistakes and Edge Cases
Even though teammate is straightforward, writers occasionally stumble when pluralizing or modifying it.
The plural is simply teammates. Don't add apostrophes unless you're showing possession (e.g., "my teammate's desk" for singular, or "my teammates' desks" for plural).
Another frequent error is treating the word as two distinct entities when formatting titles or subtitles. Even if you want to emphasize the word team, splitting it into team mate in professional copy is grammatically incorrect. Stick to the closed compound form every time.
Frequently Asked Questions
Is team-mate with a hyphen ever correct?
Some British publications and older style guides historically favored team-mate. However, contemporary style guides overwhelmingly prefer the closed compound teammate without any hyphen.
Does AP Style use teammate as one word?
Yes. The Associated Press Stylebook follows standard dictionary entries and treats teammate as a single, unhyphenated word.
Why do some spell checkers flag teammate?
If a spell checker flags teammate, your word processor is likely set to an outdated dictionary or a specific regional style guide that hasn't updated its lexicon. You can safely add it to your custom dictionary.
Can teammate be used as a verb?
No. Teammate is strictly a noun. If you want to describe the action of joining forces, use verbs like collaborate, partner, or team up.
