Honorificabilitudinitatibus, 27 letters long, is the longest English word consisting strictly of alterating consonants and vowels. An eighteen letter word with this property is epicoracohumeraler. A seventeen letter word with this property is hypovitaminosises. Sixteen letter words with this property include aluminosilicates, depolarizability, and supererogatorily. Fifteen letter words with this property include cytomegalovirus, heterozygosises, hexosaminidases, paramyxoviruses, pararosanilines, parasitological, tenosynovitides, tenosynovitises, unimaginatively, and verisimilitudes.