diaeresis or dieresis /dī-ērˈi-sis or -erˈ/

1. A mark ( ¨ ) placed over a vowel, esp the second of two adjacent ones to show that it is to be pronounced separately, as in naïf
2. A pause or break where the end of the word coincides with the end of a foot (prosody)

• humidify
• humidifying
• humidistat
• humidistats
• humidities
• humidity
• humidly
• humidness
• humidnesses
• humidor
• humidors
• humification
• humifications
• humified
• humifies
• humify
• humifying
• humiliant
• humiliate
• low-lived
• low lives
• low-loader
• low-loaders
• lowly
• Low Mass