in English is:

existentialism

Mutations

Soft:ddirfodaeth
Nasal:nirfodaeth
Aspirate:(no mutation)

Use

y ddirfodaeth hon
fy nirfodaeth i
dy ddirfodaeth di
ei ddirfodaeth ef/o
ei dirfodaeth hi
ein dirfodaeth ni
eich dirfodaeth chi
eu dirfodaeth nhw/hwy
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