key hole (keyhole)

Short noun compounds that name single, familiar objects usually close up into one word. The aperture that accepts a key is written keyhole, not key hole or key-hole. Below: a concise rule, clear hyphenation notes, realistic wrong→right examples across work, school, and casual contexts, quick rewrites you can paste, proofreading tricks, and common compound traps to watch for.

Quick answer

Use keyhole (closed compound). Replace key hole or key-hole with keyhole in formal, technical, and most casual writing.

• Closed compound: keyhole = the physical aperture a key fits into.
• Hyphen: usually only for modifiers (e.g., keyhole-shaped).
• Two words (key hole) is generally a spacing mistake or fast typing.

Core explanation: closed vs open vs hyphenated compounds

English compounds appear in three forms: open (two words), hyphenated, or closed (one word). Frequent, short noun pairs typically become closed over time: key + hole → keyhole.

• Closed (one word): keyhole, doorknob, fingerprint.
• Open (two words): high school, real estate.
• Hyphenated: often temporary compounds or compound modifiers (e.g., well-known researcher, runner-up).

Hyphenation and spacing: when a hyphen or space is acceptable

Use hyphens to avoid ambiguity (re-cover vs recover) or to join compound modifiers before nouns. The base noun in this case stays closed. Two words is usually an error, not an alternative spelling.

• Keep the noun closed: keyhole.
• Use a hyphen when the compound modifies another noun before it: keyhole-shaped opening.
• Avoid key-hole in formal documents; it reads archaic or stylistic.

• Wrong: We noticed a key-hole-shaped entrance on the blueprints.
• Right: We noticed a keyhole-shaped entrance on the blueprints.
• Wrong: He said he looked through the key hole.
• Right: He said he looked through the keyhole.

Real usage and tone: work, school, casual

Fiction and quick messages sometimes show split or hyphenated forms for effect or speed. For professional, academic, and technical writing, prefer the closed form for clarity and consistency.

• Work/professional: use keyhole in specs, manuals, and reports.
• School/academic: use keyhole in essays, lab reports, and drawings.
• Casual/fiction: split or hyphenated forms may appear but remain nonstandard.

• Work: In the maintenance log: "Clean the keyhole weekly to avoid jamming."
• School: Lab note: "We observed the specimen through the keyhole in the cabinet."
• Casual: Text: "I looked through the keyhole - weird!"

Try your own sentence

Test the whole sentence rather than the phrase alone: context usually shows whether the closed form fits better.

Examples: realistic wrong → right pairs (work, school, casual)

Short, copy-ready corrections you can paste into drafts.

• Work
  • Wrong: Please check the key hole on the server cabinet. →
    Right: Please check the keyhole on the server cabinet.
  • Wrong: The key-hole in the supply closet is stripped. →
    Right: The keyhole in the supply closet is stripped.
  • Wrong: Attach a metal guard to the key hole on the exterior door. →
    Right: Attach a metal guard to the keyhole on the exterior door.
• School
  • Wrong: She peered through the key hole at the start of the experiment. →
    Right: She peered through the keyhole at the start of the experiment.
  • Wrong: The key-hole diagram in the assignment was mislabeled. →
    Right: The keyhole diagram in the assignment was mislabeled.
  • Wrong: Ensure the key hole diameter matches the lock spec. →
    Right: Ensure the keyhole diameter matches the lock spec.
• Casual
  • Wrong: He looked through the key hole to spy on them. →
    Right: He looked through the keyhole to spy on them.
  • Wrong: I found a tiny key-hole on the antique box. →
    Right: I found a tiny keyhole on the antique box.
  • Wrong: She tapped the key hole and waited. →
    Right: She tapped the keyhole and waited.

Fix your sentence: step-by-step rewrites you can copy

Three quick checks: identify the noun, close the compound, smooth the surrounding phrase.

• Step 1: Is the phrase naming the hole where a key goes? If yes, use keyhole.
• Step 2: Replace key hole or key-hole with keyhole.
• Step 3: Read for flow; add a short clause if the sentence feels abrupt.

• Original: "The key hole needs oiling." →
  Rewrite: "The keyhole needs oiling to prevent sticking."
• Original: "She peered through the key-hole to see who was there." →
  Rewrite: "She peered through the keyhole to see who was there."
• Original: "There was a key hole at the base of the cabinet." →
  Rewrite: "A keyhole at the base of the cabinet allowed access to the lock."
• Original: "Check the key hole dimensions in the drawing." →
  Rewrite: "Check the keyhole dimensions in the drawing to ensure the cylinder fits."
• Original: "We taped over the key-hole." →
  Rewrite: "We taped over the keyhole to keep out dust."
• Original: "Key hole was clogged." →
  Rewrite: "The keyhole was clogged and required cleaning."

Memory tricks and proofreading tips

Small habits catch the split or hyphenated forms before they slip into final text.

• Search-and-replace: find key hole and key-hole and replace with keyhole.
• Autocorrect: add a rule so your editor fixes key hole → keyhole automatically.
• Style sheet: keep a short list of common closed compounds (keyhole, doorknob, bookstore) for team documents.

• Tip: Add key hole → keyhole to autocorrect and reduce future fixes.

Grammar notes: plurals, possessives, and compound modifiers

Treat keyhole as a single noun when adding endings; hyphens appear only when the compound is part of a modifier.

• Plural: keyholes. Example: "Replace faulty keyholes."
• Possessive: keyhole's. Example: "The keyhole's edge was bent."
• Modifier before a noun: keyhole-shaped (hyphenated for clarity). Example: "a keyhole-shaped slot."
• Do not split when adding endings: not key hole's or key-hole's-use keyhole's.

• Usage: Correct: "The keyhole's rim was worn."
  Incorrect: "The key hole's rim was worn."
• Usage: Correct modifier: "a keyhole-shaped notch."

Similar mistakes and compounds to watch for

Many short compounds behave like keyhole. When you spot a split or hyphen, check a current dictionary or your style list.

• Often wrongly split: doorknob (not door knob), bookstore (not book store), wallpaper (not wall paper).
• Often wrongly closed: write high school, not highschool.
• Modifier note: hyphenate compound modifiers before nouns - well-known researcher, keyhole-shaped slot.

• Pairs: Wrong → Right: "door knob" → "doorknob"; "book store" → "bookstore"; "wall paper" → "wallpaper"; "key-hole" → "keyhole"; "key hole" → "keyhole"; "highschool" → "high school".

FAQ

Is "key hole" ever correct?

Not in standard modern writing for the noun. You may see key hole in fast typing or older texts, but contemporary dictionaries list keyhole as the closed form.

Can I use "key-hole" in creative writing?

Yes. Authors sometimes use key-hole for archaic tone or deliberate style. Avoid it in formal, technical, or professional contexts.

How do I form the possessive and plural?

Treat keyhole like any noun: plural keyholes, singular possessive keyhole's. Example: "The keyhole's edge was chipped."

When should I hyphenate related phrases?

Hyphenate when the phrase functions as a compound modifier before a noun for clarity: keyhole-shaped opening. The base noun remains closed.

What's the fastest way to check other compounds?

Use a current dictionary or a spell/grammar tool. If the closed form appears in the dictionary, use it; otherwise follow the dictionary entry or your style guide.

Quick double-check

Before finalizing a document, run a quick find for key hole and key-hole and replace with keyhole. For teams, keep a short preferred-forms list so everyone uses the same closed compounds and avoids inconsistent variants.