synaeresis /sin-ēˈrə-sis/

1. The running together of two vowels into one or into a diphthong (phonetics)
2. The spontaneous expulsion of liquid from a gel (chem)

• thunder god
• thunder gods
• thunderhead
• thunderheads
• thunderier
• thunderiest
• thundering
• Thundering Legion
• thunderingly
• thunderless
• thunderlike
• thunder-master
• thunderous
• thunderously
• thunderousness
• thunderousnesses
• thunder peal
• thunder peals
• thunder-plump
• thunder-plumps
• thunders
• thunder sheet
• thunder sheets
• thundershower
• thundershowers