3 letters:
i'm

4 letters:
beim, dime, haim, heim, hime, kime, lime, lyme, mime, seim, sime, syme

5 letters:
-zyme, atime, azyme, brime, chime, chyme, climb, clime, crime, drime, glime, grime, knime, ni-mh, onfim, prime, rhime, rhyme, shime, shy'm, slime, slyme, smime, spime, stime, thym-, thyme, trime

6 letters:
9x39mm, abzyme, belime, berime, betime, delime, enlimn, enzyme, estime, hytime, infime, intime, opheim, prhyme, retime, s-mime, s/mime, ultime, untime, uptime

7 letters:
airtime, alltime, anaheim, anytime, arnheim, bedtime, begrime, berhyme, beslime, chatime, coprime, daytime, dislimb, dislimn, e-crime, e-prime, escrime, exptime, funtime, genzyme, hyazyme, isozyme, joytime, kaihime, kelheim, maytime, mercyme, mistime, mulheim, my-hime, naptime, nesheim, onetime, otohime, pastime, polheim, ragtime, runtime, ruptime, senhime, septime, solheim, sublime, teatime, twotime, upclimb, valheim, wartime

8 letters:
alextime, all-time, allozyme, amandime, analcime, bathtime, big-time, birdlime, blenheim, cinedigm, downtime, durkheim, facetime, flextime, foretime, fragtime, fulltime, halftime, isocryme, kaldheim, kamehime, key lime, kiyohime, kuenheim, lifetime, livetime, longtime, lysozyme, mahanaim, maritime, mealtime, meantime, mordheim, niflheim, noontime, off-time, old-time, one-time, oto-hime, outclimb, overtime, paradigm, parttime, passtime, playtime, realtime, ribozyme, run-time, seedtime, showtime, sinsheim, sometime, sondheim, subprime, sundheim, tacotime, termtime, two-time, waketime, waldheim, warehime, weinheim, why him?, windheim, wineheim, xenotime, zonetime

9 letters:
7.62x39mm, aforetime, aftertime, anticrime, archimime, bird-lime, blindheim, breaktime, brooklime, cat thyme, co-enzyme, down-time, dreamtime, drivetime, drms cime, everytime, eye rhyme, flexitime, florsheim, full-time, good-time, half-time, histozyme, ingelheim, jotunheim, kissanime, lead-time, life-time, long-time, lunchtime, microzyme, monorhyme, movietime, nifelheim, nighttime, oppenheim, overclimb, pantomime, part-time, peacetime, peak-time, pforzheim, pre-crime, presstime, primetime, pulmazyme, pulmozyme, quicklime, quicktime, real-time, resublime, rochelime, rosenheim, sensetime, smalltime, soda lime, spacetime, stop-time, storytime, sub-prime, trondheim, tsukihime, undernime, undertime, war crime, windchime

10 letters:
antienzyme, beforetime, bettelheim, burgertime, burnt lime, buttenheim, cefuroxime, crunchtime, cybercrime, dinnertime, dreamstime, drive-time, extra-time, first-time, floersheim, floresheim, guggenheim, hammertime, head rhyme, heppenheim, hochenheim, hockenheim, hoffenheim, mannerheim, mesenchyme, muspelheim, night-time, parenchyme, paroxetime, peace-time, prime-time, quick-lime, rock-climb, schooltime, screentime, short-time, small-time, space-time, springtime, straszheim, summertime, suppertime, sweet lime, true-crime, vice crime, werdesheim, wild thyme, wintertime

11 letters:
basil thyme, ceftazidime, clothestime, countertime, double-time, erythrozyme, harvesttime, healthifyme, multienzyme, osakabehime, pac-in-time, pseudoprime, rapid climb, silver lime, the sublime, vowel rhyme

12 letters:
amazon prime, caustic lime, closing-time, common thyme, guggenheim's, just-in-time, schlagenheim, sclerenchyme, spanish lime, thoughtcrime

13 letters:
american lime, christmastime, hydrated lime, initial rhyme, japanese lime, mise en abyme, nursery rhyme, tamayori-hime, toyotama-hime

14 letters:
creeping thyme, ectomesenchyme, internal rhyme, multi-paradigm, seine-maritime, superboy-prime, technetium-99m

15 letters:
beginning rhyme, consonant rhyme, generalizedtime, in the meantime, jason oppenheim, mother-of-thyme, mother of thyme, organized crime, polynomial-time, wals-siezenheim, zodiac maritime

16 letters:
almon-diblathaim, chloride of lime, exponential-time, michael morhaime, partner in crime, uwantme2killhim?, victimless crime

17 letters:
charente-maritime

18 letters:
once-in-a-lifetime

19 letters:
konohanasakuya-hime

20 letters:
newcastle-under-lyme, programming paradigm