2 letters:
ox

3 letters:
box, cox, fox, lox, pox, rox, sox, vox

4 letters:
boxx, brox, coxe, docs, foxx, hbox, knox, laux, ochs, vaux, vocs, woks

5 letters:
adcox, anbox, araks, atrox, autox, bachs, balks, bebox, blocs, bochs, bocks, botox, calks, chocs, cocks, comox, crocs, cubox, d-tox, dachs, detox, docks, e-box, embox, faccs, falks, flocs, gawks, glaux, groks, hawks, hocks, imbox, jocks, kkbox, lawks, lochs, locks, mawks, merox, minox, mocks, nocks, ochse, phlox, pocks, procs, redox, robox, rocks, s&box, s-box, sachs, sauks, socks, stoxx, t-box, taccs, talks, unbox, velox, vioxx, vivox, wachs, walks, x-box

6 letters:
airbox, amdocs, approx, avelox, baulks, binocs, bloc's, blocks, brocks, caulks, chalks, chocks, clocks, colfox, cowpox, crocks, dock's, dosbox, faulks, fawkes, flocks, flotox, folfox, frocks, hatbox, hawkes, heliox, hotbox, hydrox, icebox, in-box, iraq's, jawbox, jaycox, kidfox, knocks, kroc's, loches, lummox, mapbox, mattox, modocs, nitrox, outbox, outfox, pegbox, redbox, redfox, rhinox, rock's, runbox, salk's, sarbox, shocks, sigfox, simcox, skybox, smocks, stalks, stocks, talk's, tarbox, teabox, toybox, trimox, uproxx, yapoks

7 letters:
anammox, anaprox, arawaks, backbox, bandbox, beatbox, big-box, bloch's, block's, boombox, boondox, britbox, brock's, busybox, callbox, cashbox, castbox, cat box, chumbox, clock's, coolbox, cow-pox, deedbox, dicebox, digibox, dog-fox, dropbox, entonox, equinox, farebox, firebox, firefox, flummox, fluxbox, fowlpox, freebox, fundbox, gearbox, geexbox, gutwaks, hawke's, hellbox, infobox, jukebox, kit fox, listbox, lockbox, longbox, luminox, mailbox, maniocs, milkpox, mohawks, musk-ox, musk ox, okotoks, openbox, palafox, paradox, pillbox, playbox, polymox, pondoks, poorbox, postbox, red fox, rheboks, rockbox, rudebox, saltbox, sandbox, sea-fox, seedbox, shitbox, showbox, soapbox, spitbox, squawks, stock's, stocks', talkbox, textbox, thwacks, tickbox, toolbox, toy-box, toy box, undocks, unlocks, wallbox, wild ox, willcox, woodcox, workbox

8 letters:
airlocks, alms box, audiovox, bedrocks, birchbox, blackbox, blue fox, brainbox, breadbox, buildbox, call box, camelpox, catwalks, checkbox, coachbox, coin box, colorocs, crashbox, defrocks, dice-box, dice box, dreambox, drop-box, econobox, elflocks, fetlocks, glovebox, goshawks, gray fox, grey fox, gunlocks, haycocks, hemlocks, homeobox, horsebox, horsepox, jacques', jaywalks, juke-box, jury box, librivox, lightbox, loosebox, lunchbox, macaques, matchbox, mite box, moneybox, mousepox, nunataks, oarlocks, orthodox, otterbox, padlocks, paintbox, paradoxe, peacocks, petcocks, philodox, phonebox, photobox, play-box, poor box, postdocs, restocks, rockshox, rowlocks, salt-box, saucebox, scripbox, seacocks, seahawks, shylocks, skyhawks, skywalks, sleepbox, slingbox, slushbox, smallpox, smokebox, snuffbox, sonicfox, soundbox, stompbox, sweatbox, swiftfox, swinepox, toby fox, tool-box, trisenox, unblocks, unfrocks, voicebox, warlocks, waterfox, waterpox, water ox, wedlocks, whitebox, whitepox, wileyfox

9 letters:
badblocks, ballcocks, black-box, black box, black fox, boondocks, brant-fox, bufferbox, buzzcocks, cakewalks, candlebox, chromebox, cigar-box, cigar box, deadlocks, ditty-box, dry-docks, eyestalks, firelocks, flintobox, gamecocks, gogglebox, gridlocks, groovebox, gunstocks, hancock's, havelocks, headlocks, heterodox, hungrybox, idiot box, klipdachs, letterbox, linstocks, litterbox, lovefoxxx, lovelocks, mandelbox, megalobox, miter box, mitre box, money box, monkeypox, moonwalks, moorcocks, music box, penstocks, pepperbox, picklocks, pillarbox, piratebox, press box, pseudodox, rabbitpox, rattlebox, rhythmbox, searchbox, shadowbox, shamrocks, sherlocks, sidewalks, small-pox, snuff-box, spiritbox, stopcocks, strongbox, sunblocks, swine-pox, tinderbox, tomahawks, touch-box, traprocks, underdaks, voice box, warlock's, white fox, woodcocks

10 letters:
anachronox, arctic fox, backblocks, bag-in-box, ballot box, beanstalks, belle knox, billycocks, blackhawks, boardwalks, calliphlox, cellblocks, cereal box, chatterbox, chickenpox, ciclopirox, common box, cornstalks, crosswalks, dialog box, dreadlocks, echohawk's, emilia fox, fallon fox, feedstocks, flintlocks, flying-fox, flying fox, folfirinox, foreshocks, george fox, goggle-box, goggle box, goldilocks, goldylocks, gridlock's, headstocks, hollyhocks, incredibox, interlocks, leafstalks, letter-box, letter box, matchlocks, moneytalks, nifurtimox, nighthawks, outlet box, overstocks, paddle-box, pencil box, pepper-box, pepper box, phonebloks, pillar box, prompt box, roadblocks, rootstocks, sceloglaux, sentry box, shadow-box, shamrock's, sherlock's, signal box, silver fox, sleepwalks, spacewalks, squawk box, squeezebox, st jacques, tenfourfox, terrahawks, thunderbox, tinder-box, unorthodox, victorinox, virtualbox, whipstocks, window box

11 letters:
aftershocks, alpenstocks, alphablocks, amphibrachs, badderlocks, blackhawk's, charlie cox, chicken-pox, cracker box, deposit box, diamondprox, fischbach's, hammerlocks, hitchcock's, journal box, laverne cox, musical box, outsidexbox, packing box, penalty box, pouncet-box, prairie fox, raccoon fox, silverhawks, squeeze-box, squeeze box, witness-box, witness box

12 letters:
birkenstocks, breechblocks, dispatch box, european box, fall equinox, laurence fox, mountain box, neo-orthodox, numberblocks, shooting box, shuttlecocks, sparrowhawks, spatterdocks, stuffing box, weathercocks

13 letters:
asian wild ox, atlanta hawks, band-in-a-box, chocolate-box, christmas box, fermi paradox, lightinthebox, march equinox, marmalade box, pandora's box, saint-jacques, telephone box, ultraorthodox, vivica a. fox

14 letters:
greek orthodox, laughingstocks, michael j. fox, omgitsfirefoxx, pseudosmallpox, rickettsialpox, spring equinox, the desert fox, vernal equinox

15 letters:
jack-in-the-box, jewish-orthodox, nova scotia lox

16 letters:
20th century fox, autumnal equinox, eastern orthodox, jacks-in-the-box, russian orthodox, scandinavian lox

17 letters:
chicago white sox, september equinox, simpson's paradox

18 letters:
safety deposit box

19 letters:
whisky on the rocks

20 letters:
whiskey on the rocks

23 letters:
the cloverfield paradox

31 letters:
strategic arms limitation talks

3 letters:
ops

4 letters:
cops, hops, tops, sops, pops

5 letters:
crops, shops, flops, props, drops, copse, slops, elops, stops, chops

6 letters:
eumops, triops

7 letters:
lithops

8 letters:
aegilops, rynchops

9 letters:
anomalops, synagrops

11 letters:
common hops, coral drops, parascalops

13 letters:
leptotyphlops, microdipodops

14 letters:
knockout drops