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Results found in several dictionaries: Collins, Collaborative Dictionary
fossil 
  n fossile  m 
  modif 
[collector, hunter] 
de fossiles 


fossil energy 
  n énergie  f  fossile 
fossil fuel 
  n combustible  m  fossile

Collaborative Dictionary     English-French
fossil fuel n. le combustible fossile Reverso General Dictionary 
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'fossil' also found in translations in French-English dictionary
combustible fossile n. fossil fuel ~ 
non fossile exp. non-fossil Reverso General Dictionary 

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