Longest English word consisting only of vowels
Who
Euouae
Where
When
Euouae, at six letters long, is the longest English word consisting only of vowels, and, also, the word with the most consecutive vowels. Words with five consecutive vowels include cooeeing and queueing. Euouae -- medieval musical term which indicates the vowels of the syllables of "seculorum Amen," which ends the "Gloria Patri."