in English is:

inefficiency

Mutations

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

Use

yr aneffeithlonrwydd hwn
fy aneffeithlonrwydd i
dy aneffeithlonrwydd di
ei aneffeithlonrwydd ef/o
ei haneffeithlonrwydd hi
ein haneffeithlonrwydd ni
eich aneffeithlonrwydd chi
eu haneffeithlonrwydd nhw/hwy
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