3 syllables:
septical, skeptical

4 syllables:
conceptacle, dyspeptical, proleptical, protreptical, receptacle, sylleptical

5 syllables:
antiseptical, epileptical, metaleptical

7 syllables:
electric receptacle

3 syllables:
ventricle, helical, despiteful, medical, denticle, festival, segmental, reticle, vesicle, ethnical, pellicle, testicle, technical, metrical, plentiful, besprinkle, ethical, pedicel, centrical, metical, epical, chemical, aestival, bendable, credible, decimal, edental, edible, emmental, epochal, equable, estival, flexible, genital, getable, gettable, kettleful, legible, meltable, methanal, peccable, pedestal, pennoncel, pentacle, pessimal, preferable, rentable, requital, retinal, seconal, sectional, sellable, seminal, seneschal, sensible, sensual, sentinel, skeletal, spectacle, spendable, stretchable, tenable, tentacle, testable, vegetable, vegetal, vendable

4 syllables:
electrical, heretical, alchemical, unethical, prophetical, genetical, identical, nonsensical, extendible, ereshkigal, appendicle, calendrical, directional, aesthetical, symmetrical, ascetical, indelible, esthetical, angelical, putrescible, obstetrical, synthetical, acceptable, accessible, affectional, amenable, amendable, ascendable, church festival, collectable, collectible, commendable, compensable, compressible, conceptional, confessional, congenital, congressional, contemptible, contestable, conventional, correctable, correctional, defendable, defensible, delectable, dependable, detectable, detestable, digestible, dimensional, discretional, dispensable, electable, exceptional, execrable, expendable, expressible, extendable, extensible, forgettable, illegible, impeccable, impregnable, incredible, inedible, ineffable, inflectional, inflexible, injectable, insensible, intentional, intestinal, jazz festival, lamentable, obsessional, ostensible, perceptible, polemical, preventable, processional, professional, raw vegetable, recessional, redemptional, regrettable, respectable, resplendent quetzel, root vegetable, stand sentinel, susceptible, trigeminal, unbendable, unquenchable, unrentable, untellable, untenable

5 syllables:
parenthetical, homiletical, geometrical, petrochemical, imperceptible, exegetical, ecumenical, evangelical, diametrical, dialectical, hypothetical, unsymmetrical, catechetical, theoretical, oecumenical, asymmetrical, arithmetical, alphabetical, antithetical, apprehensible, bidirectional, commonsensible, comprehensible, health professional, hexadecimal, homosexual, inaccessible, incompressible, incontestable, incontestible, indefensible, indigestible, indispensable, inexpressible, inextensible, insurrectional, insusceptible, irrepressible, leafy vegetable, nonprofessional, one-dimensional, reprehensible, third-dimensional, three-dimensional, two-dimensional, unacceptable, unaccessible, unamenable, unconventional, uncorrectable, undefendable, undependable, undetectable, unexceptional, unexpendable, unexpressible, unforgettable, uninjectable, unintentional, unpresentable, unpreventable, unprofessional, unrespectable, unsusceptible

6 syllables:
incomprehensible, infinitesimal, antipathetical, heterosexual, multidimensional, omnidirectional, paraprofessional, recurring decimal, religious festival, repeating decimal, semiprofessional, unidimensional, unidirectional

7 syllables:
circulating decimal