Dyblu n - Doubling n

There are no absolute rules for using double n in Welsh. By now, spellcheckers such as Cysill have made life a little easier. However, here are a few rules (and their exceptions) which may help:

• There are two ns after an when the word following it begins with t, d, n, e.g.
  
  • an + t = annh e.g. an + tebyg = annhebyg
    
  • an + d = ann e.g. an + dymunol = annymunol
    
  • an + n = ann e.g. an + naturiol = annaturiol
    
  BUT
  
  • an + tr = anhr e.g. an + trefn = anhrefn


• There are two ns when we add a syllable to nouns ending in –nt, e.g.
  
  • dant – dannedd
    
  • cant – cannoedd
    
  • llwyddiant – llwyddiannau
    
  • peiriant – peiriannau
    
  • diwylliant – diwylliannol
    


• There are two ns when we add a syllable to nouns ending in -en or –yn, e.g.
  
  • llyfryn – llyfrynnau
    
  • dogfen – dogfennau
    
  • offeryn – offerynnau
    
  BUT
  
  • emyn – emynau
    
  • gwenyn – gwenynen
    
  • telyn – telynau


• When we add a syllable to words ending in –iwn, the n doesn't double, e.g.
  
  • cwestiwn – cwestiynau, cwestiynu
    
  • ffasiwn – ffasiynau, ffasiynol
    
  • fersiwn – fersiynau
    


• The n doesn't double in front of -wyr, -ion, -iad e.g.
  
  • diflannu – diflaniad
    
  • offerynnau – offerynwyr
    
  • ysgrifennu – ysgrifenwyr
    
  • cyfrannu – cyfraniad
    
  • gwynnu – gwynion