3 letters:
app, cap, gap, hap, lap, map, nap, pap, rap, sap, tap, yap, zap

4 letters:
asap, capp, chap, clap, crap, dapp, flap, frap, gapp, giap, happ, kapp, mapp, napp, papp, rapp, sapp, shap, slap, snap, tapp, trap, wrap, yapp, zapp

5 letters:
aacap, adcap, ancap, ascap, aslap, astap, attap, bglap, c-cap, canap, cappe, chapp, clapp, conap, cscap, decap, dolap, dovap, dulap, encap, frapp, g-rap, happe, hicap, holap, ianap, intap, irlap, ismap, janap, kappe, klapp, knapp, krapp, lappe, mappe, mcmap, micap, milap, mocap, molap, nappe, nicap, nocap, nofap, nsdap, pacap, pappe, phrap, potap, rappe, recap, remap, rocap, rolap, scrap, secap, shapp, shrap, sinap, slapp, snapp, stapp, strap, tappe, tefap, thrap, trapp, uncap, unhap, vicap, wolap

6 letters:
aercap, affrap, arcmap, attrap, barcap, beclap, belnap, betrap, bewrap, bitmap, burlap, catnap, chappe, climap, cohmap, comnap, corcap, dewlap, dognap, doolap, earcap, earlap, entrap, enwrap, etappe, fodmap, frappe, gelcap, grappe, gukbap, hubcap, icecap, intrap, inwrap, isomap, keycap, kidnap, kitsap, klappe, knappe, laplap, madcap, mbappe, medcap, mencap, midcap, milsap, mipmap, mishap, mobcap, mudcap, nadcap, neshap, niacap, p-trap, pixmap, pregap, redcap, redmap, rescap, rewrap, riprap, satrap, schapp, setapp, skycap, strapp, tencap, toecap, toxmap, trappe, unicap, unisap, unsnap, unwrap, vishap, yonhap

7 letters:
alu-cap, automap, baaskap, bandgap, bersiap, bit-map, bluecap, caltrap, cantrap, cw qapp, dirtnap, dropcap, earflap, echappe, eyeflap, flytrap, forwrap, gametap, genapap, genappe, hoodcap, huffcap, hwangap, kneecap, kylchap, libpcap, lovemap, mantrap, mid-cap, milkcap, millsap, mob-cap, ms-chap, mudflap, nearmap, nukemap, overlap, podsnap, pop-rap, rattrap, realcap, rip-rap, roadcap, roadmap, rootcap, schappe, schlapp, schnapp, shiplap, sitemap, ski cap, snowcap, specmap, stopgap, suntrap, t-strap, tap-tap, thewrap, tun/tap, unstrap, varicap, waxycap, westcap, widegap, wiretap

8 letters:
attrappe, baasskap, backslap, backwrap, beartrap, blackcap, bullcrap, claptrap, dimetapp, ettercap, firetrap, flat-cap, flat cap, foolscap, giftwrap, glooscap, golf cap, handclap, handicap, imagemap, inky cap, interlap, itk-snap, ketchapp, knee-cap, lagnappe, lens cap, lightcap, lightmap, livetrap, man-trap, mau5trap, microcap, milk-cap, mini-map, moontrap, multimap, multitap, nightcap, nordkapp, pace lap, photomap, pop-trap, rastacap, rat-trap, root cap, scullcap, semarnap, skullcap, smallcap, snipsnap, spamtrap, stop-gap, superzap, tube map, underlap, waldrapp, whatsapp, whitecap, wind gap, wordwrap

9 letters:
bootstrap, afterclap, backstrap, boobytrap, bottlecap, chinstrap, clickwrap, cloth-cap, cloth cap, cold snap, cornercap, deathtrap, death cap, draintrap, flip-flap, gift-wrap, gift wrap, goldfrapp, guttatrap, heightmap, honeytrap, housewrap, iron trap, jockstrap, lagniappe, large-cap, micro-cap, mousetrap, night-cap, priestcap, sand trap, screencap, skull-cap, small-cap, small cap, snip-snap, soundtrap, sparadrap, spark gap, tarnkappe, tent flap, trade gap, vibraslap, watch cap, water gap, water tap

10 letters:
after-clap, bitch-slap, blackstrap, booby-trap, booby trap, brandysnap, chin strap, click-wrap, cradle cap, fool's cap, gingersnap, hukbalahap, jockey cap, mobile app, nachtkrapp, peaked cap, rattletrap, relief map, sailor cap, saran wrap, shower cap, shrinkwrap, shufflecap, sketch map, solar trap, speed trap, spinal tap, steel-trap, steel trap, watchstrap, wentletrap

11 letters:
bathing cap, bokkeum-bap, bubble wrap, choke-strap, contour map, ginnungagap, liberty cap, pocket flap, rawoop-snap, scott stapp, semordnilap, service cap, shrink-wrap, take a crap, thunderclap, weather map, wishing cap, wrestlecrap

12 letters:
baseball cap, bishop's cap, blasting cap, cervical cap, garrison cap, landing flap, noah schnapp, overseas cap, plastic wrap, radiator cap, stocking cap, swimming cap, thinking cap, thunder-clap, toboggan cap, yachting cap

13 letters:
novochlorocap, openstreetmap

14 letters:
cumberland gap, nba salary cap, openweathermap, percussion cap, shoulder strap, slip-slop-slap

15 letters:
corona-warn-app, distributor cap, maria von trapp

16 letters:
santhosh prathap

6 letters:
lablab