3 letters:
ode

4 letters:
bode, coad, code, coed, goad, load, lode, moad, mode, node, owed, road, rode, roed, toad, toed

5 letters:
-pode, -toed, abode, amode, anode, aoede, bloed, bowed, brode, c.o.d, choad, chode, co-ed, diode, enode, erode, fcode, frode, g.o.d, glode, goede, grode, inode, isode, knode, lowed, moede, mowed, ncode, ocode, p.o.d, pagod, rhoad, rhod-, rhode, roede, rohde, rowed, scode, sewed, shoad, shode, sowed, spode, tcode, thode, towed, troad, trode, vcode, xcode

6 letters:
acnode, annaud, b-mode, bbcode, binode, blowed, byroad, c-code, code-e, crowed, dadoed, decode, demode, demoed, dynode, encode, flowed, friode, g-code, genode, gloede, glowed, goedde, growed, haloed, hpcode, i-mode, inroad, kanode, knowed, kosode, linode, m-code, nosode, ogdoad, onload, opcode, oxgoad, p-code, pagode, pogoed, recode, reload, sarode, scrode, showed, shrode, siloed, slowed, snowed, soloed, stowed, strode, unload, unowed, upload

7 letters:
alamode, altmode, anyroad, appcode, armload, asplode, barcode, bedload, bencode, bibcode, busload, cameoed, carload, cascode, cathode, cladode, commode, corrode, crunode, didmoad, elbowed, episode, explode, fenowed, folioed, forbode, geocode, gumroad, halloed, helloed, heptode, holloed, hoptoad, implode, intcode, ip code, kathode, kermode, kommode, liflode, lolcode, methode, miscode, netcode, netload, no-load, nonroad, offload, offroad, outmode, outroad, outrode, patnode, payload, pentode, placode, preload, radioed, redcode, relcode, rexroad, richaud, rodeoed, sarcode, sa node, schrode, spinode, strowed, subcode, sympode, tacnode, throwed, tiptoed, unbowed, unicode, vaivode, vanload, waiwode, waywode, webnode, woiwode, zincode, zipcode

8 letters:
antinode, autocode, autoload, backload, backroad, bar code, baseload, bestowed, bestrode, boatload, bordlode, borrowed, buttload, bytecode, cartload, cartroad, caseload, copycode, cs pcode, cs qcode, displode, download, fallowed, farrowed, flowcode, forebode, freeload, freenode, furisode, hemipode, highroad, keratode, kowtowed, livecode, livelode, lycopode, manucode, maxicode, megapode, metapode, mobisode, monomode, monopode, nematode, nielloed, off-load, omnicode, openload, org-mode, out-mode, overload, overrode, palinode, passcode, phyllode, polypode, postcode, pre-code, punycode, railroad, scancode, shedload, shipload, silkroad, ten-code, threnode, timecode, tramroad, tuxedoed, undergod, unitrode, uudecode, uuencode, veracode, webisode, winnowed, workload, zip-code, zip code

9 letters:
accropode, afterload, agua toad, area code, a la mode, bell toad, buffaloed, bushiroad, byte-code, case load, coachload, crosscode, crossroad, dead load, dvcpro hd, eckenrode, eigenmode, elektrode, extracode, fire code, hydathode, hydrogode, iconicode, incommode, internode, karmacode, kozhikode, live load, lowbrowed, macrocode, main road, melampode, microcode, mimencode, multimode, neodamode, omphalode, outflowed, phylocode, planeload, plateaued, platinode, post road, rainbowed, ring road, shellcode, side road, silk road, skid road, slip road, staminode, stomatode, superload, swelltoad, tardisode, tide-rode, torpedoed, trainload, transcode, tree toad, trematode, truckload, true toad, underload, wagonload, wind-rode

10 letters:
4kdownload, choral ode, color-code, color code, discommode, dvc pro hd, foreshowed, front-load, furbelowed, greek mode, highbrowed, legal code, lymph node, megaupload, morse code, motherload, nesselrode, order code, overflowed, penal code, photodiode, pseudocode, royal road, sourcecode, texas toad, trunk road, unbestowed, unborrowed, unsorrowed

11 letters:
access road, anticathode, binary code, bridle road, church mode, dull-browed, gymnocytode, health code, horned toad, konami code, manifestoed, mustachioed, object code, on the road, postal code, pseudo-code, ribbed toad, secret code, source code, tailed toad

12 letters:
authenticode, black-browed, cold-cathode, depeche mode, ethical code, femi ogunode, horatian ode, load-to-load, machine code, midwife toad, moustachioed, musical mode, photocathode, pindaric ode, private road, surinam toad, the ice road, western toad, woody strode

13 letters:
american toad, arterial road, beetle-browed, brazen-browed, building code, computer code, european toad, medieval mode, old town road, take the road, write in code, yosemite toad

14 letters:
anonymous;code, ascending node, gregorian mode, operation code, richard ayoade

15 letters:
descending node, yellowbrickroad

17 letters:
elevated railroad, iata airport code, pacific tree toad, southwestern toad, the da vinci code

18 letters:
visual studio code

19 letters:
american green toad, ecclesiastical mode, eurasian green toad, grand funk railroad, semiconductor diode

20 letters:
light-emitting diode, underground railroad

21 letters:
error correction code

22 letters:
universal product code

24 letters:
international morse code, major depressive episode

26 letters:
asynchronous transfer mode, south american poison toad

27 letters:
acute schizophrenic episode