3 syllables:
be double, b double, dreadable, pleadable, readable

4 syllables:
exceedable, impleadable, obedible, unreadable

5 syllables:
inolvidable, machine-readable, unsucceedable

3 syllables:
tenable, equable, estival, medical, stretchable, sensual, skeletal, sextuple, pessimal, sensible, meltable, vegetable, vendible, retinal, festival, aestival, flexible, spectacle, sentinel, pedestal, sepulchral, bendable, legible, methanal, peccable, epochal, plentiful, sectional, seconal, decimal, vegetal, seneschal, genital, skeptical, ethical, gettable, tentacle, testable, jezebel, seminal, rentable, pennoncel, requital, spendable, chemical, pentacle, beatable, eatable, feasible, fleeceable, peaceable, reachable, reasonable, regional, seasonal, speakable, squeezable, teachable

4 syllables:
impregnable, acceptable, ineffable, conventicle, dimensional, condemnable, detectable, expressible, compensable, congressional, inflectional, electable, dispensable, preventable, unquenchable, processional, injectable, digestible, adjectival, atenolol, professional, illegible, heliacal, confessional, comestible, inflexible, delectable, insensible, ascendable, defensible, trigeminal, regrettable, contemptible, defendable, correctional, extendable, untenable, centesimal, amendable, accessible, commendable, amenable, intestinal, respectable, affectional, collectible, lamentable, expendable, directional, correctable, perceptible, receptacle, contestable, execrable, recessional, polemical, conceptional, dependable, detestable, congenital, ostensible, preferable, impeccable, forgettable, collectable, compressible, susceptible, obsessional, conventional, intentional, exceptional, extensible, achievable, appealable, appeasable, believable, conceivable, defeasible, infeasible, perceivable, redeemable, repeatable, unbeatable, uneatable, unfeasible, unreachable, unreasonable, unspeakable

5 syllables:
hexadecimal, unexceptional, incompressible, apprehensible, comprehensible, inextensible, bidirectional, inaccessible, undependable, three-dimensional, neurochemical, indispensable, unconventional, nonprofessional, two-dimensional, unintentional, indigestible, hypothetical, inexpressible, reprehensible, irrepressible, pyrotechnical, insurrectional, indefensible, planetesimal, unforgettable, insusceptible, health professional, unacceptable, homosexual, unprofessional, inconceivable, indefeasible, irredeemable, irretrievable, note receivable, unachievable, unappealable, unappeasable, unbelievable, unimpeachable, unperceivable, unredeemable, unrepeatable, unretrievable

6 syllables:
omnidirectional, semiprofessional, heterosexual, recurring decimal, unidirectional, repeating decimal, multidimensional, unidimensional, paraprofessional, accounts receivable