missing hyphen in '10 story window'

When two or more words together describe a following noun, they usually form a compound modifier and need a hyphen to show they act as a single idea. Missing that hyphen can change meaning or make a sentence hard to parse.

Quick rule

Hyphenate multiword modifiers when they come immediately before the noun they modify - unless the modifier begins with an -ly adverb or the compound is an established open or closed form.

• Before a noun: hyphenate - a five-minute walk, a well-known researcher.
• After a noun: usually no hyphen - the walk was five minutes; the researcher is well known.
• Don't hyphenate adverb + adjective when the adverb ends in -ly - a highly regarded study (no hyphen).

Core explanation (what to hyphenate and why)

A compound modifier (compound adjective) is two or more words that together describe a noun: five-minute break, long-term goal, user-friendly interface. When the compound sits before the noun, a hyphen ties the words so readers treat them as one unit.

Key exceptions and checks:

• If the first word ends in -ly, don't hyphenate (a highly sought position).
• Some compounds are established as open (high school student) or closed (notebook); follow a dictionary or style guide.
• Spell-out numbers and fractions used adjectivally are hyphenated (a twenty-two-page report, a one-third share).

• Checklist: Is the phrase directly before a noun? Do the words act jointly as a single descriptor? Is the first word not an -ly adverb? If yes, hyphenate.
• When in doubt, rephrase: move the modifier after the noun or convert to a prepositional phrase (a plan for the long term).

Hyphenation rules (practical, copy-ready)

Use a hyphen for number+unit modifiers (a two-week notice), spelled-out fractions (a one-third share), and joint adjectives or prefixes (well-known actor, user-friendly app).

Don't hyphenate adverb (-ly) + adjective, compounds after the noun, or established open compounds unless your style guide says otherwise.

• Spell out and hyphenate compound numbers from twenty-one to ninety-nine when used adjectivally: a twenty-one-page report.
• Use suspended hyphenation when listing several modifiers: short-, medium-, and long-term plans.
• Check a dictionary for compounds that have become single words (email vs e-mail) or standard open forms.

• Numbers: Wrong: a twenty one page essay →
  Right: a twenty-one-page essay
• Fraction: Wrong: a one third share →
  Right: a one-third share
• -ly adverb: Wrong: a highly-rated study →
  Right: a highly rated study (no hyphen)

Examples - wrong → right (copy these into your edits)

Apply the same pattern whenever a multiword descriptor appears before a noun.

• General: Wrong: High quality furniture →
  Right: High-quality furniture
• General: Wrong: Ten story window →
  Right: Ten-story window
• General: Wrong: Long term plan →
  Right: Long-term plan
• General: Wrong: Small size dog →
  Right: Small-sized dog
• General: Wrong: Well known author →
  Right: Well-known author
• General: Wrong: A five minute break →
  Right: A five-minute break
• Work:
  Wrong: She took a part time role on the project. →
  Right: She took a part-time role on the project.
• Work:
  Wrong: We have a two week deadline for the launch. →
  Right: We have a two-week deadline for the launch.
• Work:
  Wrong: Prepare the year end report by Friday. →
  Right: Prepare the year-end report by Friday.
• Work:
  Wrong: a user friendly dashboard →
  Right: a user-friendly dashboard
• Work:
  Wrong: a long overdue invoice →
  Right: a long-overdue invoice
• School:
  Wrong: I wrote a ten page paper on climate change. →
  Right: I wrote a ten-page paper on climate change.
• School:
  Wrong: The long term assignment is due next month. →
  Right: The long-term assignment is due next month.
• School:
  Wrong: Calculate the grade point average for each student. →
  Right: Calculate the grade-point average for each student.
• School:
  Wrong: a well known theory →
  Right: a well-known theory
• Casual:
  Wrong: He is an open minded person. →
  Right: He is an open-minded person.
• Casual:
  Wrong: That was a last minute decision. →
  Right: That was a last-minute decision.
• Casual:
  Wrong: Download the user friendly app. →
  Right: Download the user-friendly app.
• Casual:
  Wrong: a not for profit group →
  Right: a not-for-profit group

Real usage and tone - when writers relax the rule

In instant messages or casual chat, writers often drop hyphens (I had a last minute change). That's usually fine among friends. In professional, academic, or published writing, prefer hyphens for clarity.

Headlines and labels sometimes omit small words for space, but when ambiguity is possible keep the hyphen. In contracts, product names, or technical specs - where precision matters - follow a consistent hyphenation style.

• If readers must parse numbers, dates, or measurements quickly, hyphenate (a three-year forecast).
• If tone is informal and ambiguity is unlikely, omission may be acceptable.

• Tone: Casual chat: "I had a last minute laugh about it." (fine). Formal email: "Please note the last-minute changes to the schedule."
• Legal: Use hyphens in labels with legal consequences: "two-year warranty" not "two year warranty".

Rewrite help - copy-and-paste fixes

Pick a rewrite below or follow the simple patterns shown.

• Rewrite:
  Original: His research is long term. →
  Rewrite: His research is part of a long-term study.
• Rewrite:
  Original: We need a better looking interface. →
  Rewrite: We need a better-looking interface.
• Rewrite:
  Original: She completed a well deserved win. →
  Rewrite: She completed a well-deserved victory.
• Rewrite:
  Original: The committee made a last minute decision. →
  Rewrite: The committee made a last-minute decision.
• Rewrite:
  Original: I have a two week notice period. →
  Rewrite: I have a two-week notice period.

Try your own sentence

Test the whole sentence rather than the phrase alone - context usually makes the right choice obvious.

Spacing, hyphens vs en dash vs em dash (short guide)

Hyphen (-) joins words (well-known). En dash (-) denotes ranges or relationships (2010-2014, Boston-New York). Em dash (-) sets off interruptions or parenthetical thoughts. Hyphens have no spaces; dash spacing depends on your house style.

• Hyphen: well-known author (no spaces).
• En dash: 2010-2014, pages 10-12 (no spaces in most styles).
• Em dash: The result-despite earlier data-was clear. (spacing varies by guide)

• Dash note: Use the correct dash for the job; don't substitute a hyphen for an en dash in ranges.

Memory tricks and quick editing habits

Use these quick checks when proofreading.

• Before-noun test: If the words come immediately before a noun and describe it together, hyphenate.
• The -ly test: If the first word ends in -ly, don't hyphenate (highly regarded).
• Rephrase test: Move the modifier after the noun - if it still makes sense, consider rewording to avoid a hyphen.

• Practice: Spot "two week schedule" before a noun? Add hyphen: two-week schedule.

Similar mistakes and grammar traps

Missing hyphens often come with other errors: wrong dash type, incorrect hyphenation after -ly adverbs, failure to use suspended hyphens, or confusion between noun and adjective compounds.

• re-cover vs recover: a hyphen can change meaning.
• Suspended hyphenation: short-, medium-, and long-term plans.
• Open vs closed compounds: check a dictionary or your style guide.

• Trap: Incorrect: a highly-rated film →
  Correct: a highly rated film (no hyphen with -ly adverb).
• Trap: Incorrect: re cover the sofa → Correct (if you mean "cover again"): re-cover the sofa; recover means to get better.
• Trap: Incorrect: small business owner (when used adjectivally before another noun) →
  Correct: small-business tax rate

Soft call-to-action

Make a two-second hyphen check part of your final proofread: scan for multiword modifiers before nouns, apply the -ly rule, then hyphenate if needed.

For repeated checks, use a grammar tool that flags hyphenation issues and offers quick rewrites.

FAQ

Do you hyphenate compound adjectives after the noun?

Usually no. When the compound comes after the noun, hyphens are typically unnecessary (The artist is well known). Keep the hyphen before the noun (a well-known artist). Exceptions exist for clarity or fixed expressions.

Should I hyphenate numbers like twenty one in front of a noun?

Yes. Spelled-out compound numbers from twenty-one to ninety-nine used adjectivally are hyphenated (a twenty-one-page paper). If the number follows the noun, hyphenation is unnecessary (The paper is 21 pages long).

Is it wrong to hyphenate adverb + adjective phrases like "highly-rated"?

Don't hyphenate when the first word is an -ly adverb. Write "a highly rated study" not "a highly-rated study."

When should I use an en dash instead of a hyphen?

Use an en dash for ranges and some compound relationships (2018-2020, Boston-New York route). Use hyphens to join words into compound modifiers (well-known artist).

How can I quickly check a sentence for missing hyphens?

Mini-check: find multiword phrases immediately before nouns, ask whether they act together as one descriptor, rule out -ly adverbs, and then hyphenate. If unsure, rephrase the sentence or move the modifier after the noun.

Check the whole sentence before you send it

Reading the sentence aloud or reordering its parts often makes the correct hyphenation obvious-do that final check before you hit send.