Have you ever wondered whether compound words such as “monthlong” should be spelled as one word, as a hyphenated phrase, or as two separate words?

I spent some time looking up the commonly used compounds listed in The Associated Press Stylebook and Libel Manual and checking the recommended spellings there against the recommended spellings in William Sabin’s The Gregg Reference Manual and The American Heritage Dictionary.

Here’s what I found. You’re welcome to print a copy for reference.

Solid compounds (whether used as adjectives, adverbs, or nouns):

afterthought; anytime; anywhere; awestruck; backup; backyard; beforehand; breakdown; breathtaking; buildup (also build-up); burnout; byproduct (also by-product); cannot; caregiver; carryover; checkout; churchgoer; citywide; cleanup; colorblind; cooperative (but co-op in its shortened form); copyedit (also copy-edit); countryside; coworker (also co-worker); bankcard; database (also data base); daycare (also day care); daylong; easygoing; extracurricular; falloff; freelance; frontline (also front line); fundraiser (also fund-raiser); fundraising (also fund-raising); ghostwrite; goodwill (also good will); grass roots; grownup (also grown-up); groundwater; hardcore; holdup; homeowner (but home ownership); hourlong; inpatient; kickoff; lifestyle (also life-style, life style); makeup (also make-up); marketplace; meantime; monthlong; nationwide; nevertheless; noncompliance; nonconforming; nonconformity; nonetheless; nonprofit; notwithstanding; nowhere; officeholder; onboard (also on-board); ongoing; online; outpatient; overexposure; overgeneralization; overgeneralize; paperwork (also paper work); percent; policymaker, policymaking (also policy-making); postscript; preempt, preemptive; printout; proactive (also pro-active); proofread; pothole; redheaded (but red-haired); rollout; schoolmate; schoolroom; schoolteacher; schoolwork; schoolyard (but school day and school year); somewhere; spreadsheet; springtime; startup; statewide; stockholder; stockroom (also stock room); storyteller; summertime; tablecloth; thereof; timeline; timesaving; tossup; touch point; turnaround; voicemail; waitperson; webpage (also web page and Web page); website (also web site and Web site); weekday; weekend; weeklong; whiteout; wintertime; workbench; workday; workflow (but paper flow); workforce; workgroup (also work group); workload; workout; workplace (also work place); workroom; worksheet; workstation; worktable; workweek; workwoman; wrongdoing; yearlong

Hyphenated compounds (when used as adjectives, adverbs, or nouns):

able-bodied; absent-minded; ad-lib; A-frame; check-in; child-care (as an adjective; also childcare as an adjective; child care as a noun); clean-cut; clearing-house (also clearinghouse); close-up; co-insurance (also coinsurance); co-op (but cooperative in its long form, and cooperate as a verb); co-payment (also copayment); email (also e-mail); empty-handed; fact-finding; father-in-law; far-flung; far-off; far-ranging; follow-through (also followthrough); follow-up (also followup); front-runner (also frontrunner); frame-up; free-for-all; get-together; get-tough; G-string; half-mast; half-staff; hand-picked; hanky-panky; hi-fi; high-tech; ho-hum; hush-hush; in-depth; in-law; in-network; know-how; life-size; mind-blowing; mind-boggling; mother-in-law; narrow-minded; nitty-gritty; not-for-profit; on-site; one-sided; passer-by; pell-mell; pooh-pooh; red-haired (but redheaded); red-hot; re-elect, re-election; roly-poly; second-rate; self-service; shrink-wrap; sign-in; sign-on; soft-spoken; straight-laced; strong-arm; strong-willed; time-consuming; T-shirt; U-boat; U-turn; V-neck; voice-over; vote-getter; walk-through (as a noun); warm-up; weak-kneed; well-being; well-to-do; wheeler-dealer; word-of-mouth; worn-out; write-out; year-end

Spaced words:

African American (also African-American); after all (also afterall); cash flow; child care (as a noun; child-care or childcare as an adjective); course work; every time; fact sheet; food shelf; health care (also healthcare); help desk; life span; mind frame; more so; on site (but on-site review); paper flow (but workflow); profit sharing (but profit-sharing arrangement); pro forma; pro rata; school day; school year (but schoolmate; schoolroom; schoolteacher; schoolwork; schoolyard); time frame (but timeline); time saver; vice president (and similar terms--formerly hyphenated compounds); waiting room; word processing (but word-processed material); work release

Words whose spelling changes

according to how they are used

Spaced words as noun phrases or adverbial phrases; hyphenated compounds as compound adjectives (or unit modifiers) preceding nouns:

day to day (as in We worked day to day), day-to-day (as in our day-to-day routine); door to door, door-to-door; eye to eye, eye-to-eye; long distance, long-distance (but always long-distance in reference to telephone calls, as in I ran a long distance in a long-distance race to call you long-distance); long term, long-term; one time, one-time; out of bounds, out-of-bounds; out of court, out-of-court; out of network, out-of-network; out of pocket, out-of-pocket; right to work, right-to-work; roll call, roll-call; note: second-rate (in all uses); side by side, side-by-side; white collar, white-collar; working class, working-class

Solid compounds as indefinite pronouns; two words to single out a member of a group:

anybody, any body (as in any body of water); anyone, any one (as in any one of you); anyway, any way (as in any way you look at it); everyone, every one; nobody, no body

Spaced words as verbs with prepositions used as adverbs; solid compounds as nouns or adjectives:

back up (as in Be sure to back up your files), backup (as in The sergeant called for backup); build up (as in You need to build up a resistance to this bug), buildup (as in The military buildup is worrisome); check off, checkoff; check out, checkout; check up, checkup; clean up, cleanup; crack up, crackup; cut back, cutback; cut off, cutoff; hand off, handoff; hand out, handout; hold out; holdout; make up, makeup; pick up, pickup; roll out, rollout; set up, setup; shut down, shutdown; smash up, smashup; speed up, speedup; stand off, standoff; stand out, standout; take off, takeoff; take out, takeout; take over, takeover, take up, takeup; wind up, windup; work out, workout; work up, workup

Spaced words as verbs with prepositions used as adverbs; hyphenated compounds as nouns or adjectives:

call up (as in Let’s call up the reserves), call-up (as in The call-up came at a bad time); check in, check-in; follow through, follow-through; follow up, follow-up; push up, push-up; cover up, cover-up; hands off, hands-off; send off, send-off; shake up, shake-up; sign in, sign-in; sign on, sign-on; start up, start-up; tie in, tie-in; tie up, tie-up; trade in, trade-in; trade off, trade-off; walk up, walk-up; warm up, warm-up; write out, write-out

Spaced words as nouns; hyphenated compounds as verbs:

spot check (as in The spot check was a surprise), spot-check (as in If you can’t proofread the document, at least spot-check it)

Spaced words as articles or adjectives with nouns; solid compounds as adjectives:

a while (as in for a while), awhile (as in awhile later); a long time, longtime; every day, everyday; health care (healthcare); under water, underwater

Spaced words as adverbs with adjectives; hyphenated compounds as adjectives preceding nouns:

so called (as in He was so called because he was foolish), so-called (as in The so-called leader of the group)

Spaced words as prepositions with adverbs; solid compounds as adjectives or adverbs:

over all (as in The coffee spilled over all my papers), overall (as in Overall, things aren’t so bad)

Spaced words as adjectives following nouns; solid compounds as adjectives preceding nouns:

under way (as in The remodeling is under way), underway (as in underway refueling)

Spaced words as adjectives and nouns; solid compounds as adjectives:

every day (as in Read every day), everyday (as in my everyday routine)

Spaced words as adverbs; hyphenated compounds as adjectives:

upside down (as in The pizza landed upside down), upside-down (as in The picture was upside-down)

Solid compounds as nouns; hyphenated compounds as adjectives:

grownup (also grown-up), grown-up

Spaced words as adjectives with nouns; hyphenated compounds as adjectives or nouns:

left hand, left-handed, left-hander; right hand, right-handed, right-hander