Preexisting or Pre-Existing: Which One is Correct?

Language evolves, and sometimes that means tiny details like a single hyphen spark big debates. One common question many writers, editors, and even professionals in healthcare and law grapple with is this: Should you write preexisting or pre-existing?

The difference might seem minor, but the implications stretch across industries, documents, and clarity in communication. Let’s dive deep into this hyphenation debate and explore which version is correct, why it matters, and how to decide which form to use in your writing.

Quick Summary

Wondering whether to write “preexisting” or “pre-existing”? Both are technically correct, but usage depends on style guides, context, and clarity. The hyphenated form—pre-existing—is often used in formal, legal, and medical writing. Meanwhile, preexisting (without the hyphen) is increasingly common in modern, digital, and informal texts. Major style guides like AP prefer pre-existing, while dictionaries like Merriam-Webster accept both. The key is consistency and audience awareness. This guide breaks down definitions, real-world examples, usage tips, and synonyms to help you choose the right form every time.

The Core Question: Is It “Preexisting” or “Pre-Existing”?

You’ll see both forms used in professional and casual writing. But are they interchangeable?

• Preexisting (no hyphen) is more common in modern writing, especially in digital formats.
• Pre-existing (with a hyphen) is often used in formal documents, especially in legal or medical fields.

The choice depends heavily on context, consistency, and style guide preferences. But both forms are considered correct by major dictionaries—they simply represent different stylistic choices.

What Does “Preexisting” Mean Anyway?

Preexisting Definition

The term “preexisting” or “pre-existing” is an adjective that refers to something that already existed before a certain time, event, or action. It generally implies prior existence or presence.

Pre Existing Meaning in Common Use

• In Insurance: A health condition that existed before a person’s health benefits started.
• In Law: A situation, contract, or relationship that existed before a change in legal status.
• In Tech: A system or software that was already in place before an upgrade or new installation.

“The patient’s preexisting condition was not covered by the new insurance policy.”

Why the Confusion Exists

The uncertainty over preexisting or pre-existing stems from how compound words evolve in the English language. Let’s explore the key factors.

1. Compound Word Evolution

Many compound modifiers start out as hyphenated terms. Over time, as they become more familiar, the hyphen often disappears.

Examples:

Older (Hyphenated)	Modern (Single Word)
e-mail	email
on-line	online
web-site	website
pre-existing	preexisting

2. Style Guide Variations

Not all style guides agree on the rules for compound modifiers. Some advocate for clarity over tradition.

3. Digital Influence

Search engines and content management systems often favor non-hyphenated terms. “Preexisting” is easier to search and index.

Usage According to Top Style Guides

Let’s look at how authoritative style guides treat the word:

Associated Press (AP) Style

• Prefers hyphens in compound adjectives before a noun: “pre-existing condition”
• Example: “Coverage does not apply to pre-existing conditions.”

Chicago Manual of Style (CMS)

• Recommends consistency throughout a piece.
• Tends to allow closed compounds (no hyphen) when the meaning is clear.

Merriam-Webster Dictionary

• Lists “preexisting” as the primary spelling.
• Hyphenated version appears as a variant.

Oxford English Dictionary (OED)

• Accepts both forms, with a slight preference toward “pre-existing.”

Quote from Merriam-Webster:
“Preexisting: existing at an earlier time; especially: existing before a particular point in time or event.”

Which Should You Use? Key Decision Factors

Consistency Matters Most

Once you choose one form, stick with it throughout the document. Inconsistent usage reduces readability and professionalism.

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Readability and Tone

• Use “preexisting” in less formal, modern writing where simplicity is valued.
• Choose “pre-existing” when clarity might be compromised or when writing for traditional audiences.

Audience and Context

Audience	Recommended Form
Medical professionals	Pre-existing
Academic readers	Pre-existing
Blog or casual readers	Preexisting
Legal documents	Pre-existing
Tech documentation	Preexisting

Origin and Evolution of the Term

The word “pre-existing” dates back to early 18th century English, where hyphenation was the norm for compound adjectives. But as compound words became more commonly used, especially in digital and tech writing, the hyphen began disappearing.

Timeline:

• 1700s: Hyphenated use in medical/legal documents
• 1950s-80s: Continued dominance of “pre-existing”
• 2000s-Present: Shift toward “preexisting” in tech and online platforms

Real-World Examples in Sentences

Pre-Existing in Use

• “The pre-existing condition clause disqualified many applicants.”
• “He was unaware of the pre-existing lease agreement.”

Preexisting in Use

• “The software was integrated into the preexisting infrastructure.”
• “Her symptoms were related to a preexisting autoimmune disorder.”

Comparison Table:

Usage Context	Preferred Form	Sentence Example
Health Insurance	Pre-existing	“Coverage excludes pre-existing conditions.”
IT Infrastructure	Preexisting	“Works with preexisting systems.”
Legal Contracts	Pre-existing	“Subject to pre-existing laws.”
Informal Blogs	Preexisting	“Based on preexisting knowledge.”

Synonyms & Related Terms

Sometimes, the best way to avoid the hyphen debate is to rephrase. Let’s explore some strong pre-existing synonym options.

Synonym/Related Phrase	Meaning	Best Use Case
Existing prior	Something already in place	Technical writing
Already present	Present beforehand	Casual writing
Prior condition	Previously diagnosed or known condition	Healthcare
Previous	Earlier occurrence or state	General writing
Established	Confirmed and accepted as existing	Business/legal documents

Pro Tip: If clarity is more important than style, a synonym like “prior condition” often works better.

SEO Implications: Which Version Ranks Better?

Digital writers must consider how search engines interpret both spellings.

Google Search Trends

According to Google Trends, “preexisting” generally has a higher search volume, especially in the US, likely due to its prevalence in health and tech content.

Search Volume Comparison:

Keyword	Monthly Global Searches
preexisting	18,000+
pre-existing	9,000+
pre-existing synonym	1,300+
preexisting definition	1,600+
pre existing meaning	900+

Content Strategy Tip:

Use both spellings strategically within a post to capture diverse search queries, but do it naturally to avoid keyword stuffing penalties.

Final Verdict: Which One Should You Use?

Both “preexisting” and “pre-existing” are correct, but your choice should depend on:

• The style guide you follow
• The audience you’re writing for
• The formality of your content
• The platform or industry standard

Use “preexisting” if:

• You’re writing online, for general readers
• You want modern, SEO-friendly spelling
• You’re aiming for quick readability

Use “pre-existing” if:

• Your content is formal, academic, legal, or medical
• You’re following AP or CMS style strictly
• You need maximum clarity in dense or technical text

Quick Reference Table

Criteria	Pre-Existing	Preexisting
AP Style	Yes	No
CMS	Yes	Yes (if consistent)
Medical Usage	Common	Common
Formal Publications	Preferred	Less formal
Casual/Modern Writing	Less used	Preferred
SEO/Online	Lower ranking	Higher ranking

Conclusion

This isn’t just a battle of hyphens. It’s a reflection of how English continues to shift with usage, technology, and time. So whether you’re writing a legal brief, health insurance form, or a blog post, knowing when to use preexisting vs. pre-existing gives your writing both accuracy and polish.

Choose wisely, stay consistent, and write with clarity.