3 syllables:
competence

4 syllables:
incompetence, with competence

5 syllables:
omnicompetence

6 syllables:
four stages of competence

7 syllables:
displaying incompetence

3 syllables:
wantonness, concreteness, profitless, populous, ominous, omnibus, concaveness, obtuseness, opulence, providence, cognizance, spotlessness, prominence, oblateness, prophetess, confidence, consonance, commonness, populace, consequence, somnolence, documents, dominance, consciousness, vomitus, oxalis, bottomless, provenance, populus, polypus, continence, romulus, watchfulness, pompousness, columnists, communists, conscienceless, continents, godlessness, honestness, modestness, monuments, noxiousness, obstinance, occupants, oculus, omphalus, onymous, protestants, rottenness, scolytus, slothfulness, squalidness, stolidness, strophanthus

4 syllables:
predominance, self-confidence, hypostasis, hydrolysis, hypothesis, endogamous, abdominous, metropolis, sarcophagus, synonymous, incontinence, concomitance, monogynous, ignobleness, saprophagous, self-consciousness, recognizance, obsoleteness, monoclinous, necropolis, anonymous, propositus, passionateness, diplodocus, inconsequence, esophagus, reconnaissance, monotonous, convolvulus, monogamous, homologous, oppositeness, autonomous, incompleteness, apophysis, acropolis, nitrogenous, anthophilous, subconsciousness, acrogenous, acromphalus, ammotragus, androgenous, anthophagous, apogamous, apophasis, astomatous, autogenous, autologous, autolysis, carpophagous, cryptogamous, cytolysis, eponymous, exogamous, gymnopilus, hippotragus, idolatress, improvidence, lose consciousness, melophagus, obnoxiousness, oesophagus, panonychus, pathologists, phytophagous, psychologists, sarcolemnous, taurotragus, uncommonness, uropsilus, with confidence, zoophagous

5 syllables:
amylolysis, anthropophagus, vote of confidence, electrolysis, entomophilous, opisthognathous, adorableness, megalopolis, hippopotamus, stream of consciousness, variableness, anemophilous, anisogamous, loss of consciousness, peloponnesus, acantholysis, air reconnaissance, campylotropous, creeping oxalis, disconsolateness, fibrinolysis, genus oxalis, haematolysis, hematolysis, heterologous, nonautonomous, nonnitrogenous, ophiophagus, proteolysis, semiconsciousness, stephanopoulos, unselfconsciousness

6 syllables:
adrianopolis, bacteriolysis, bacteriophagous, megalobatrachus

7 syllables:
genus hippopotamus

8 syllables:
urinary incontinence, alcoholics anonymous, electronic reconnaissance

15 syllables:
international society for krishna consciousness